California, Temperatures, and Acres Burned

Guest Post by Willis Eschenbach

Inspired by the work done by Robert Rohde attempting to link May to October temperatures and rainfall to fires, I thought I’d take a look at the acres burned over the years. Rohde compared the rainfall and temperature records and highlighted the largest fires. However, this gives only a few data points. I wanted a larger view of the situation.

So instead of major fires, I looked at the areas burned every year, which are available here. There is complete data from 1959 to 2016, and the last two years are available here and here.

The first thing I did was run a multiple regression on the data, using both May to October temperature and May to October rainfall to see how well they would predict the area burned. To my great surprise, I found out that rainfall is not significantly correlated with the area burned. Here is that result:

               Estimate Std. Error t value Pr(>|t|)    
(Intercept)   -13393785    2502402  -5.352 1.61e-06
Temperature      203834      35791   5.695 4.52e-07
Rainfall         -46812      35591  -1.315    0.194

Temperature is significant (right-hand column, p-value 4.52e-7), but rainfall is far from significant (p-value = .19). So I ignored rainfall for the rest of the analysis.

Next, I graphed the acres burned, and ran a linear regression on the data. Figure 1 shows that result:

Figure 1. Total areas burned by year, 1959-2018 (red line) and linear least squares trend line (blue line).

Note that the p-value of the line is quite good (right column, p-value = .00000004). The R^2 value (bottom line) shows that the straight line explains 41% of the variance in the acres burned.

Then I looked at the connection between temperature and acres burned. Figure 2 shows that result:

Figure 2. Total areas burned by year, 1959-2018 (red line) and acreage estimated from the variation in May – Oct temperatures (blue line).

Curiously, that looks a lot better than the straight line … but note that there is only a slight increase in the amount of variance explained (44% variance explained by temperature versus 41% for the straight line). This proves once again that our eyes are tuned to see patterns even when none are there … consider the constellations of the night sky as a prime example.

Finally, I looked at the errors in the temperature based estimate of the acres burned. Figure 3 shows the difference between the temperature-based estimate of the area burned and the actual acreage burned.

Figure 3. Errors of the estimate.Total areas burned by year, 1959-2018, minus the acreage estimated from the variation in May-Oct temperatures. The red line is a seven years Full-Width Half Maximum (FWHM) Gaussian average of the data. The vertical dotted blue line shows that in 1994, logging was stopped in much of the state in a vain attempt to protect the Spotted Owl.

Here is the oddity of the Figure 3 graph. In the first part of the record, up to the early part of the 21st Century, the temperature generally overestimates the acres burned.

But since then, the temperature has greatly underestimated the number of acres burned.

This is clear evidence that the recent large wildfires are not due to the variations in temperature as is widely claimed.


• Using variations in May to October rainfall do not improve the estimate of the acreage burned. In other words, May to October rainfall doesn’t add anything to an estimate done using May to October temperature alone.

• The variations in May to October temperature are only slightly better than a straight line in estimating the variations in area burned.

• The recent very large areas burned are not the result of variations in May to October temperature. As I pointed out in my last post, the decade over decade changes in temperature are nowhere near large enough to explain the recent increase in the area burned. We must look elsewhere for the causes of these large fires.

h/t to Steven Mosher for pointing out the Rohde analysis.

[UPDATE] Some folks didn’t like the data I used, so here’s some more:

I’m home now, and the smoke is not too bad. Not as bad as it was in the Central Valley or in San Francisco on the way back here. We’re in the yellow area on the California coast north of San Francisco. Smoke map available here, click on “Vertically Integrated Smoke” or “Near Surface Smoke”.

Figure 4. Smoke map. Red is the thickest smoke. The Camp Fire is burning north-east of Sacramento.

My best wishes and hopes for the future for all of those affected by the fires, and my condolences for those who have lost friends, family, or homes.



PS—My usual request. When you comment, please quote the exact words you are referring to, so we can all be clear on what you are discussing.

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November 14, 2018 3:21 am

The wise old (spotted) owl knows the reason.

November 14, 2018 3:25 am

Willis, your final conclusion was “The recent very large areas burned are not the result of variations in May to October temperature. As I pointed out in my last post, the decade over decade changes in temperature are nowhere near large enough to explain the recent increase in the area burned. We must look elsewhere for the causes of these large fires.”

The wild card in any analysis of wildfires is the cause, and if memory serves somewhere about 85% of all wildfires are caused by humans. Maybe population would be better used for comparison.


Reply to  Bob Tisdale
November 14, 2018 5:39 am

Bob –
85% of fires may be initiated by humans one way or another, okay.
But in a climate like California has, that accumulated fuel is gonna burn anyway. Just a matter of when.
A careless cigarette, a power transmission arc, a lightning strike. That’s why forest management is so important for the preservation of human life.
Willis’ analysis is masterful. Can’t admire the guy too much. I, too, saw Robert Rohde’s brilliant graphic, and I would have complimented him upon it if I had any inclination at all to indulge in Twitter, but Willis has asked the right question and come up with a most ingenious illustration of what’s going on. Just wish the Governor and his people would actually engage with some of this, but they won’t.

Further observation – You might recall that, 15 or so years ago, a big wildfire ripped through a town in Victoria, Australia, killing ?200+ of the inhabitants. The pictures of that place are eerily simlar to the pictures of Paradise, both before and after. The layout of the town amongst the trees especially. Lessons should have been taken

Reply to  mothcatcher
November 14, 2018 10:43 am

Rainfall would also contribute to fuel buildup. Does season winter rains increase fuel for burning in the same way CO2 may flow temperature?

Reply to  Wally
November 14, 2018 12:18 pm

In a nutshell, yes. Almost everyone in the PNW knows a wet winter/spring season brings more brush growth. That more growth of adds to fuel load when it dries out over the summer (and it almost always a dry summer). Unfortunately our overlords don’t allow the common people protect their property so we have to stand back and watch it burn. Insanity it encouraged and sanity is derided in this part of the country.

Robert B
Reply to  Wally
November 14, 2018 2:24 pm

Montana ranks number 1 in acres burnt – about 10% more than California in 2017 – with about a quarter the number of fires.
Obviously a lot more than temperature affects the size of fires. Spring growth and drying out over summer along with strong winds and large swathes of land with no natural fire breaks.

Andy Wills
Reply to  mothcatcher
November 14, 2018 2:06 pm

Hi mothcatcher,

the fire you are referring to was horrific even by Australian standards. We are well aware of the dangers involved and those of use who aren’t in the current crop of SJW’s know full-well what is required during fire season (we know we have a fire season). Unfortunately it would seem that we do not learn from past endeavor.

I was personally involved in the 1983 ‘Ash Wednesday’ bushfires that raged across the southern states, seconded from my Navy duties, in a hellish whirlwind that had the hundred in our group (squads of ten) on the ground armed with rakes and shovels, day and night.

As is the want to politicise the weather, these types of events are common across Australian history, noting (with some sarcasm) that the levels of CO2 were lower in 1983 and for the many fires prior to that. What has increased, I note with some disdain, the numbers for socialist control-freaks has increased over the same period (I know, correlation is not necessarily linked to causation).

The land-owners in the 1983 fires were prohibited from clearing their land. This takes my back to my comment above about learning from our mistakes.

Have a great day,


Reply to  Bob Tisdale
November 14, 2018 5:47 am

Bob – yup

Not only are humans the proximate cause of the initial ignition of most wildfires, but human management practices have been well known for many decades now to be the cause of conditions that make wildfires much worse than typical in unmanaged wildlands. Primarily because we have allowed way too much fuel to collect by fighting small fires, and by failing to properly clear understory fuel sources.

Yes, the professional forest managers in USFS and BLM have more or less learned this lesson, and for decades have been engaged in prescriptive burns to reduce fuels. But that only applies in well managed forests, which excludes many privately owned forest lands, of which many owners are negligent in their forest management practices, and of course it excludes such active forest management practices most designated wilderness areas. So perversely, while we allow “natural” fires in the wilderness areas to burn, we don’t allow active forest management practices that would tend to limit the magnitude of natural burns.

Hence we got the humongous wildfire in Yellowstone Park back in 1988, which resulted in nearly 800,000 acres (more than 1/3 of the entire park) of ancient lodgepole pine forest to burn in our oldest and most beloved National Park.

When you factor in the other human causes of LARGE WILDFIRE BURNS, the percentage likely approaches 100%.

Reply to  Duane
November 14, 2018 10:07 am

Privately owned forests are still regulated by the state. That makes management almost impossible, and definitely ruinously expensive to attempt to obtain permits.
The fault is not primarily the owners of forests. (I no longer own property in California. I don’t have a dog in this fight – except that California smoke is nasty in the Reno area.)

Gerald Machnee
Reply to  Bob Tisdale
November 15, 2018 12:53 pm

Add humans, more houses, electricity to the mix and see what happens.

Ben Wouters
November 14, 2018 3:33 am

Maybe oktober-may rainfall is more relevant to determine how susceptible the forests are for fires in the following summer.

Reply to  Ben Wouters
November 14, 2018 5:35 am

I’m baffled by the rain thing. Forest fire fighters pray for rain.

… we watch the weather, we watch the wind, and we pray for rain …link

I have heard comments like that since forever. Surely rainfall during the fire season is really relevant.

Tom Halla
Reply to  commieBob
November 14, 2018 6:48 am

CommieBob, it is May to October rain, and it rarely rains in California during those months normally. Most of the rain is October to May.

J Mac
Reply to  Tom Halla
November 14, 2018 8:33 am

You have it right, Tom!
It is the heavy winter and spring rains that drive significant growth of under story brush, grass, and fuel load over the summer, not the minimal summer and fall rains.

Reply to  Tom Halla
November 14, 2018 1:01 pm

Rainfall patterns are regionalized and vary a lot by geography. In CA, summers and falls are very dry, but in the four corners area to the east, the summer is the wet season, at least part of the summer, typically in July and August that is called the “monsoon season”… with late spring and early summer being very dry with high winds so very high risk for wildfire. In the Pacific Northwest and northern Rockies, the late summer and early fall is the dry season, more like CA. In the southeast US, the late winter and spring is the dry “fire season”.

Tom Halla
Reply to  Duane
November 14, 2018 1:33 pm

I should have noted “except in the Mojave”.

Reply to  Duane
November 15, 2018 5:02 am

Nope, at least in my corner of the Southeast USA, where we get 4.5 feet of rain each year on average (+/- 0.5 feet standard deviation, approximately). November through May is the wet season, averaging a bit more than an inch per week (1.5 inches per week in March, our wettest month). Summer and early autumn are the relative dry times, though active tropical seasons may belay that somewhat. The driest months are September, slightly less than 1 inch of rain per week, on average, and October, about 0.75 inches of rain per week, on average. October and November are the most common times for controlled burns to reduce fuel load. Thunderstorms may happen on any given day all year, too. We are also in our secondary tornado season now.

Steve Reddish
Reply to  commieBob
November 14, 2018 9:33 am

I think firefighters pray for rain because that is the only thing that makes it possible to put out fires in today’s overly thick forests.


Michael S. Kelly, LS, BSA, Ret.
Reply to  Ben Wouters
November 15, 2018 2:36 am

“Maybe oktober-may rainfall is more relevant to determine how susceptible the forests are for fires in the following summer.”

Agreed. I lived in Southern California for 28 years. The rains, when they come, always do so in the October-May time frame. Summer rains are rare. And the fire seasons were always predictable. A series of wet winters would build up the brush, and then one or two dry years would end with lots of fires.

When I arrived in San Bernardino in late 1980, the entire face of the mountain to the north was on fire. That was the Panorama Fire, and several friends lost their homes to it.

I experienced quite a number since then, and the pattern was evident to everyone.

Joel O’Bryan
November 14, 2018 3:43 am

“The vertical dotted blue line shows that in 1994, logging was stopped in much of the state in a vain attempt to protect the Spotted Owl.“

Technically that’s true. But like the Delta smelt and the San Joaquin River, both were just a ploy to stop something the Environmental lobby wanted stopped. If it hadn’t been spotted owls or Delta Smelt, the environmental movement would have found something else (another critter) to use because predator prey ratios naturally swing up and down in any ecosystem.

The problem with logging of course is that it artificially compensates for an anthropogenic wild fire suppression management strategy. Wild fires (unrestrained forest fires or fires on chapparal-grass lands) once century or so has always been part of the natural ecosystem, until fire suppression altered that equation because fires put human property and lives at risk. So now the wild fires become explosive bombs ripping through over-burdened forest paradises and overgrown chapparal-filled canyon vistas due to heavy ground fuel loads with dead trees and brush/ground detrius.

Now the winter rains of December-March will come to create more misery with mudslides.
And those too will predictably be blamed on CC.

BTW, nice work Willis.

Joel O’Bryan
Reply to  Joel O’Bryan
November 14, 2018 3:49 am

too, not to. (I miss edit)

Reply to  Joel O’Bryan
November 14, 2018 5:50 am

There may be a difference between naturalists and environmentalists. Here’s Freeman Dyson’s take on naturalists:

Naturalists believe that nature knows best. For them the highest value is to respect the natural order of things. Any gross human disruption of the natural environment is evil. Excessive burning of fossil fuels is evil. Changing nature’s desert, either the Sahara desert or the ocean desert, into a managed ecosystem where giraffes or tunafish may flourish, is likewise evil. Nature knows best, and anything we do to improve upon Nature will only bring trouble. link

Dyson contrasts untrammeled naturalism with conditions in England:

I spent my formative years in a land (England) with great beauty and a rich ecology which is almost entirely man-made. The natural ecology of England was uninterrupted and rather boring forest. Humans replaced the forest with an artificial landscape of grassland and moorland, fields and farms, with a much richer variety of plant and animal species. Quite recently, only about a thousand years ago, we introduced rabbits, a non-native species which had a profound effect on the ecology. Rabbits opened glades in the forest where flowering plants now flourish. There is no wilderness in England, and yet there is plenty of room for wild-flowers and birds and butterflies as well as a high density of humans. Perhaps that is why I am a humanist.

Human habitation and land use can be very good for biodiversity. That’s the bottom line isn’t it?

Reply to  commieBob
November 14, 2018 8:44 am

Dyson has a rather romantic view of the British countryside with respect to rabbits. At about the time he left for the US rabbits were a plague in the UK (insufficient predation). I recall walking in the countryside and when you looked over the hedge into a field hundreds of rabbits would run away. Everyone ate rabbits, much cheaper than chickens! However their effects on the crops were disastrous, you literally couldn’t shoot enough of them. As a result a fatal disease, myxomatosis, was introduced in the early 50s which almost wiped them out, I didn’t see another wild rabbit for over 10 years. Apparently the numbers are increased but not where they were before the 50s.

Ron Long
Reply to  Joel O’Bryan
November 14, 2018 5:53 am

Here’s a thought for Joel, Bob, Willis: I grew up in Douglas County, Oregon, the heart of timber industry for the USA. My brother and I had a summer job for a logging company where we were on rapid-fire-response duty in the forest near the logging operation. We did small jobs like road repair, brush removal, etc waiting for a fire to start. Two fires started that summer in our area, one due to lightening and one at a worksite (cause unknown). However, we jumped on both no matter what the cause and held it in check until Forest Service crews arrived. Then comes the Spotted Owl and logging activities and the attendant rapid-response crews, are cut way back. Maybe the correlation Willis detected has a real explanation? Spotted Owl anyone?

Eric H.
Reply to  Ron Long
November 14, 2018 11:28 am

Sure, I hear it tastes like chicken. I was in Douglas County last week. I have relatives in Yoncalla.

November 14, 2018 3:52 am

More humid air from the Pacific flows into California.

A C Osborn
November 14, 2018 3:59 am

Mr Eschenbach, this graph for Oregon tends to back you up, note the major difference in Acres Burnt.

comment image

November 14, 2018 4:01 am

The dry Arctic air reaches Mexico.
comment image

Cardin Drake
November 14, 2018 4:01 am

There has been an insignificant increase in temperatures and an insignificant decrease in rainfall in California. However, there has been an 80% reduction in wood harvested from California. It doesn’t take a genius to figure out which variable matters when it comes to wildfires.

Reply to  Cardin Drake
November 14, 2018 5:32 am

The linked report on the condition of forests in California is revealing. The inventory of dead trees is staggering:
The state has spent billions on intermittent power generators in a vain attempt to reduce CO2 output. The money would have been better spent managing forests. That would actually reduce the real threat of wild fire disaster.

News reports on the wild fires often implicate Climate Change but at least there is an abundance of information on the condition of the forests and the high fuel load waiting for a spark; which are readily available and provided free.

Reply to  Cardin Drake
November 14, 2018 8:47 am

I’m glad I searched for “coyote” before I made a quick reply with the same link. I can understand the folks for whom climate change is the go to explanation for this kind of stuff, but almost all of them refuse to take even a second glance at what could be much larger influences.

Steve O
November 14, 2018 4:22 am

To be explicit about what is implied, the chart on Errors By Year seems to indicate that a new variable was introduced. The final step is to add “log factor” and calculate how many acres burn every year in order to protect owls habitat.

Steve Fitzpatrick
November 14, 2018 4:53 am

Hi Willis,
The question that comes to my mind is if the increase in area burned happened in places where there would have been logging if it had not been blocked by legal action. I could be mistaken, but I suspect the area near Los Angeles which burned recently was unlikely to have been logged. Do you know if logging would have been taking place in the Camp region? I also wonder about the influence of rainfall in the previous winter; does more rain in the preceeding winter generate more underbrush fuel?

Clyde Spencer
Reply to  Steve Fitzpatrick
November 14, 2018 8:51 am

Yes and no. The area around Pulga, the supposed ignition point for the Camp Fire, is extremely rugged and probably wouldn’t have been logged because of accessibility. Also, the serpentinite in the immediate area doesn’t support dense pine growth. However, if you go out to Google Earth, you can see evidence of clear cut logging north of Paradise. The real problem seems to be that the human infrastructure in Paradise is actually more flammable than the surrounding wild land, despite a significant fire having ‘thinned’ things considerably in Paradise 10 years ago.

No, the recent fires in Southern California didn’t have harvestable timber. However, 100 years ago, nobody would have been foolish enough to build an expensive, flammable home in the dry scrub-lands.

Reply to  Clyde Spencer
November 14, 2018 10:37 am

This is an image from the area around Pulga near where the fire is believed to have started. As you can see it’s not a logging area, what I read was that there was an alarm from here about burning grass in the cleared area below the power line.
comment image?w=810

Steven Mosher
November 14, 2018 5:04 am

interaction term between temp and rainfall might be what you want

Neutron Powered, High Side, Sideways Racer
Reply to  Steven Mosher
November 14, 2018 5:53 am

or some of the wildfire potential indices.

Dan Hughes
Reply to  Steven Mosher
November 14, 2018 5:55 am

or some of the wildfire-potential indices that are used around the world.

Peta of Newark
November 14, 2018 5:08 am

It is an old landscape
It is doing what ‘old’ things do – degenerate and die.
One may venture that ‘Fires are cancer’
And how many times does the ‘medical treatment’ of cutting out the tumour simply cause it to spread?
So much for logging or ‘removing the fire load’

Possibly very advanced diabetes. A much better analogy.
Bits fall off, but especially, the body loses its ability to manufacture fat.
Hence the expression ‘Fat of the Land’ A ‘fat’ land is a healthy and productive one. Ask your local farmer for confirmation.

The fat in this case is soil organic matter. A nutrient deficiency or severe nutrient imbalance means the land cannot manufacture ‘fat’ anymore. Soil organics are what makes a landscape= ’rounded’ or ‘rolling’
It becomes thin. Gaunt. Wasted. Wrinkled. Craggy. (Old man) Masculine. Angular. Corroded or Eroded

Residents of Ca, step outside and look around. (others use Google maybe)
What do you see? In one word. First Impression.
First answer *only* accepted and *no* thinking time

Here’s your choice of words:

Is there any fat out there?
If not, you iz in da big Big Trouble.
Better find that cure for diabetes and pretty quickly…

Reply to  Peta of Newark
November 14, 2018 10:36 pm

The obese are much, much more likely to suffer from both diabetes and cancer, so your analogy fails.

Fire is a natural process. It cannot be otherwise in an ecosystem that includes both dry fuels and sources of ignition. Native peoples new this, and fuel-reduction burning was a wise response.
Only moderns have assumed that because we can mostly control fires, that we should. To use a more accurate analogy, it is like trying to stop wolves from killing deer, then wondering why the deer over-graze and destroy their ecosystem.

HOT fires burn all organic matter and leave the soil loose and subject to erosion. COOL fires leave the soil humus intact, but open the understory to permit light entry and release bound up nutrients, resulting in growth.

Native peoples knew this, too.

Jeff H
November 14, 2018 5:22 am

Rainfall during the May – October period may not be correlated. The issue is rain prior to or early in the fire season followed by lack of rain later. Rain provides for more vegetative growth which then dries and becomes fuel later. Joe Bastardi predicted a rough fire season in California based on the abundant early rain. It always gets dry at some point. Other point is high temperature follows drought; high temperatures due not cause drought they are the result.

Zack aa
Reply to  Jeff H
November 14, 2018 11:22 am

Re: Bastardi’s reflexive counter to GW=fire theory is his own idea that seasonal rains grow fuel for western fires the next season strike me as, how to say it?

I watch his daily updates regularly and it always annoys me he never comments about things west of the Ohio River. But then he finally does and I have to pause and remember how I really appreciate his zealous dedication to Atlantic hurricanes and how all the global indicators of snow events line up for a particular zipcode in central PA.

November 14, 2018 5:24 am

Acreage burned depends on several variables difficult to quantify: strength and duration of winds, remoteness of the burn area, cause of the fire, time to fire-fighting response, magnitude of fire-fighting effort, etc. It’s not surprising the ones easiest to measure, rainfall and temperature, have little correlation.

Dennis Bird
November 14, 2018 5:45 am
November 14, 2018 5:56 am

No matter how a fire ignites, a forest fire becomes dangerous because of the weather conditions allowing it to start and to grow. The potential for forest fires is often indicated by the Haines Index (HI) that has been widely used for operational fire-weather forecasts in regions of the United States, Canada, and Australia. Several studies have shown a positive correlation between HI and observed fire activity. And yes there is correlation between HI and oscillations like ENSO.

“The Haines index (HI) is a fire-weather index that is widely used as an indicator of the potential for dry, lowstatic-stability air in the lower atmosphere to contribute to erratic fire behavior or large fire growth. This study examines the interannual variability of HI over North America and its relationship to indicators of large-scale circulation anomalies. The results show that the first three HI empirical orthogonal function modes are related respectively to El Nino–Southern Oscillation (ENSO), the Arctic Oscillation (AO), and the interdecadal sea ~ surface temperature variation over the tropical Pacific Ocean. During the negative ENSO phase, an anomalous ridge (trough) is evident over the western (eastern) United States, with warm/dry weather and more days with high HI values in the western and southeastern United States. During the negative phase of the AO, an anomalous trough is found over the western United States, with wet/cool weather and fewer days with high HI, while an anomalous ridge occurs over the southern United States–northern Mexico, with an increase in the number of days with high HI. After the early 1990s, the subtropical high over the eastern Pacific Ocean and the Bermuda high were strengthened by a wave train that was excited over the tropical western Pacific Ocean and resulted in warm/dry conditions over the southwestern United States and western Mexico and wet weather in the southeastern United States. The above conditions are reversed during the positive phase of ENSO and AO and before the early 1990s.”
My synopsis is

November 14, 2018 5:58 am

Lookup these topics. Fuel load. Ladder fuels. Probability of ignition. Area burned will be a combination of these factors. This is well understood science.

There is good software out there that does this.

Historically, most of the US burned on periods of 10 to 30 to 100 years. Suppressing fires each year just pushes the problem into the future, catastrophically.

The long term solution is to burn like the native indians did and to manage the forests next to the urban areas more closely. Ie thinning and regular backfiring to keep fuel load on the ground near zero. We also need fire codes that require inflammable roofs and vegetation management.

November 14, 2018 6:00 am

Stay safe Willis and Anthony! I note that you did the analysis for the ‘wildfire’ season May – Oct, the events of this week appear to be related to the non-arrival of the rainy season this November. Historically as I understand it the fires in October that cause the most damage in part due to the Santa Ana winds that occur then. Any extension of the season into November seems likely to increase the likelihood of major fires? Looking at the Oroville catchment area data they’ve had 0.24″ of rain since Oct 1st, before that the last rain was May 26th. Last year rain started on Oct 19th with about 5″ by this time.

Mike Wryley
November 14, 2018 6:10 am

Watching my house catch fire in Malibu Park last Friday afternoon, I can offer the following observations;
1. The hill sides have very few trees, the bottoms of the valleys have a few.
2. The plant matter on these area burns like a Christmas tree after it’s set in your house for three weeks, imagine tens on thousands of those trees per acre.
3. Now add a 50-60 mph wind coming in from one direction, ocean breaze from another.
4. Humidity is 20 percent.
5. The intense heat causes anything that normally would to be too green to catch fire under normal circumstances to burst into flames.

The effect is like a blowtorch, impossible to stop, and very efficient at burning thousands of acres in a single day. I used to wonder how people and firefighters get killed in something as obvious as a brush fire, I now know. These fires can easily project themselves hundreds of yards beyond what appears to be the fire line. Small fire tornado appears to pickup material as I had gravel bouncing off the hood of my car a half mile or more from the fire line.

Unfortunately, this tinderbox scenario is the status quo in much of southern California. The only solution to the undergrowth problem that has any practically would be millions of very hungry goats and thousands of miles of fences, and then trying to seed the areas with a nonflammable plant that provides some form of watershed.

November 14, 2018 6:19 am

My thoughts are with you all.

In Ontario we’ve just been provided with this information: ‘Woman Claims She Was Contacted about Faulty Power Line Prior to Fire’:

My apologies if this is old news but it triggered for me a memory of a story, that seems to have disappeared now, of the loss of a massive number of acres here in northern Ontario, which was first reported to have been started by equipment used by an industrial wind turbine company in the midst of ruining one of our wilderness treasures.

Reply to  Sommer
November 14, 2018 6:29 am

This is the original story. referred to above, where CBC reported the cause:

Joe Born
November 14, 2018 6:54 am

Have you done the regressions on the subset of the data that extends only to 1994?

November 14, 2018 6:56 am

An interesting first analysis. But to get a good correlation the auto-correlation should be removed from both series first.

November 14, 2018 7:10 am

It is suggested forest management is the problem. This could be true for forests. But Paradise is not a forest. So why was it destroyed?
Perhaps house construction needs investigation. If a house fire happens and the wind blows then the current situation suggests the fire will spread to other houses (see great fire of London).

November 14, 2018 7:11 am

The American Meterological Society has just released a report into last year’s fires in N Cali. I didn’t realise that the power companies had put anti trip devices into their equipment. Instead of tripping off and staying off until a human intervenes, they now trip off and on and off and on etc. Which causes sparks…

Reply to  Teddz
November 14, 2018 10:06 am

True, for most Utilities now, an Auto Recloser (AR) is used to deactivate the line temporally for 8-10 seconds, and then if no fault is detected, then the AR closes to line and reenergizes the circuit voltage. When it is hot out, there is more line sag, and when faced with a larger wind, then more line slap happens. If this keeps happening over and over, then the chance of a spark becomes more likely with every slap and auto reclosing event to spark up a fire. It may be better to revert back to the manual thermal fuse, where when it blows, a new $7 fuse has to be manually reinstalled. (e.g. a 6 amp cutout fuse on a single phase 25 KV line)

This way, someone actually has to drive out to the general area where the fault happened and install a new fuse at the top of the pole. A general inspection is then carried out of the entire line to observe any hanging branches etc, whatever is causing the fault. Line slap is more difficult to assess as there is no real evidence of anything happening if you don’t see it happen, except maybe a sagging primary line up top between spans.

The Auto Reclosers are real handy in that they function automatically, and generally keep the power on which is a real blessing for home owners in a windy rainstorm. (and cost less for the Utility over time) However, if something like line slap is happening in a raging Santa Ana wind event when it is Extreme High burning conditions, then a thermal cut out fuse shuts the power off until a human investigates and installs a new fuse might be a better option. Maybe something obvious like a sagged line or a branch/tree limb arcing is then spotted that can be remedied for that problem. It does look like power line companies have some responsibility here.

Reply to  Earthling2
November 14, 2018 11:03 am

As you can see in the photo I linked to of the area believed to have been near the source of the fire the landscape is very rugged and manual inspection would take a long time. You’ve got high voltage power supply lines from hydroelectric dams up in the mountains being buffeted by high speed Santa Ana winds. The areas being supplied would possibly suffer multiple loss of service?

Reply to  Phil.
November 14, 2018 12:19 pm

I haven’t looked up exact details, but the Orville Dam generating plant is producing 800+ Mw High Voltage 3 Phase out of their sub station. Probably 500 KV on huge steel towers. Those aren’t the issue with starting fires that I am aware of. The problems are local Distribution 3 Phase 25 Kv or especially Single Phase 14.4 Kv distribution lines that are slapping between the neutral and the primary, serving the local community on multiple feeders which are locally protected by cut out fuses or voltage regulators/reclosers at different points.

Most local transformers are served by their own cut out fuse, (or should be) just to protect that transformer from things like local lightening strikes. If that fuse blows, especially if there is a fault on the 240V Triplex side, it only affects that service past that transformer and not even the entire feeder line. It all depends on the code for that area and utility how everything is protected. Not all feeder distribution lines would lose power, only the affected one. That still might mean 300-400 local customers though, but not the entire region.

Usually, the local distribution feeders at single phase 14.4 Kv follow existing roads and local R/W’s as they feed the neighbourhood through the trees and urban forest. This is also usually the weakest link in proper brushing and clearing of dead danger trees in the R/W. They are easy to inspect by just driving the route. This is where a lot of these Auto Voltage Regulators/Reclosers are located.

The question is, do we want the inconvenience of a local power outage every line slap with a manual reset/human inspection/installation of a local fuse that affects a smaller subset of the population, or take the chance with the automatic voltage reclosers that continued sparks from a line slap that keeps getting worse as that sag increases from arcing/heating the aluminum/steel #2 ACSR (Aluminium conductor steel-reinforced cable) with every line slap fault. At some point, it just melts and the line is physically separated, although it is has probably caused a fire by then if it is conducive to burn. Perhaps most of the year on the reclosers, but able to set to manual fusing might be a partial solution. The first line slap event could also cause the first spark/fire. No easy solution, although I read that the local utility can cut the power completely in severe Santa Ana wind events when things are extremely dry and conducive to burn.

Reply to  Phil.
November 14, 2018 2:15 pm

You may be correct Phil…I am seeing reports of PG&E experienced an outage on the Caribou-Palermo 115 kV transmission line in Butte County and also nearby to where the fire started. But PG&E is also denying that it was this 115 kV transmission line, and said this line had already be de-energized and work had been pre-planed and had sent an email to Betsy Ann Cowley where the transmission tower was located on her private land.

There seems to be confusion about which transmission line caused a fire, and which was the report to the Regulator of an incident. I also see a report of what looks like a downed lower voltage distribution feeder line in the same vicinity, which I was discussing above. Obviously both can cause sparks, although usually a high voltage transmission line is built to a much higher standard, with no vegetation issues at the elevation of the high tension wires. But there appears to be equipment malfunction, so not sure what that means. A spark could definitely fall from the wires and start the grass on fire and then it is gone. I think we will have to wait for the investigation, and police have sealed off access to this area as a crime scene.

But I also see PG&E is quickly getting on the bandwagon with the climate change CAGW being the principal cause behind all these wild fires. I guess this will be their insurance of ‘last resort’ and appeal to the State and the Governor for relief.

Reply to  Teddz
November 14, 2018 11:01 am

Sounds like reclosers. After tripping from a short they automatically try to reconnect 3x before remaining open and requiring manual intervention. They save a lot of work because sometimes dummies like me miscalculate when they drop a tree and unintentionally slap the line (large tree on slope detached from stump when it fell, which changed the arc of fall). All I had to do was reset my house circuit breaker, and the neighbors caught a break.

Peter Parke
November 14, 2018 7:35 am

Perhaps the increase of forest fires in settled ares of CA, as well as Greece and other areas with a Mediterranean climate, has to do with the eucalyptus tree and its continually growing popularity. This tree is extremely flammable, as some in Australia are aware of. This tree has all sorts of advantages, including rapid growth, repelling insects and even having a pleasant aroma, so we might as well just live with its flammability.

Steven F
Reply to  Peter Parke
November 14, 2018 11:15 pm

Eucalyptus is not native to California. Some was planted in the past by farmers and is occasionally used in landscaping for homes. There probably isn’t any at the location where the fire started. Most of the trees were native pines and fire trees which are also extremely flammable.

November 14, 2018 7:39 am

A very serious situation for many. Please be safe. I ran into a series of videos posted by Juan Browne on his Blancolirio youtube channel. He has some interesting observations including a video of the area where the fire started two days before. Apparently the area had been burned and most of the forest growth was destroyed leaving basically dry scrub growth in the canyon. He has some interesting observations and is at risk himself. He gives a very reasoned account unlike most of the media. Here is the first of his reports. Others can be found on his channel. By the way he has probably the best series of reports/videos on the Oraville Dam disaster and its reconstruction. Well done and very interesting.

Reply to  DanH
November 14, 2018 8:13 am

Yes Juan’s coverage of Oroville has been great as has his coverage of the recent fire (he lives about 30 miles from it). As an ex-firefighting pilot (currently an airline pilot) he brings a great insight into the Ca fires, he’s posted on this subject over the last few years. He was actually in the mountains near where the fire started few days before and showed how dry the ground was and commented on the extended dry season this year (only 0.25″ since the end of september, last year by this time they’d had 5″).

Curious George
November 14, 2018 8:17 am

Maybe it would correlate with a number of regulations? I need a permit to burn my dead wood, and I can do it only during approved “burn days”. I’ll speculate that there may be 25 burn days in a year.

Steven F
Reply to  Curious George
November 14, 2018 1:18 pm

“Maybe it would correlate with a number of regulations?”

You would probably get a better correlation with the budget for controlled burns and thinning. Funding for the US forest service is very low for this. California has been increasing the budget for this but fire fighting costs has increased even faster than the budget. Most of the money for fire fighting this year has already been spent in after only a couple of months. It currently looks like California will need to spend about 1.5 billion a year on fire fighting, controlled burns and thinning.

Clyde Spencer
November 14, 2018 8:31 am

You said, “…the straight line explains 41% of the variance in the acres burned.” Not to be pedantic, but that should be 40.1%.

November 14, 2018 8:57 am

The fall rains are a few weeks late showing up this year, and combined with excessive fuel loading from years past, have now combined with an ignition source to create a potential monstrous fire. It could have happened anywhere else, but unfortunately it conspired within an area of rural and city interface. I am so sorry for the people suffering through this. This is very tragic and is my worst nightmare, living within my own managed woodlot forest. When it is hot and dry, even after a few dry weeks in May/June, anything is possible with the right wind and ignition source.

If there had been a decent fall rain in October or early November, these present conflagrations would have probably waited for another opportunity to burn. Sooner or later, it is the nature of everything to burn in a firescape evolved ecology. It is tragic that we are now in the mix with human habitation. We either have to adapt with human intervention in reducing fuel loading/ignition sources or suffer the consequences. Much of the land is not commercial forestry so it all can’t be blamed at the foot of logging or the spotted owl, although that could certainly be a huge factor where forest fires actually happen where commercial forestry could be happening and at least offer some management and reducing potential areas of burn.

Perhaps we should be looking at artificial cloud seeding to coax out any possible rains, when there is any opportunity to do so? I know in the Philippines, where the Province of Bohol in the Central Visayas has been in prolonged drought and has begun targeting cloud seeding to fill specific dam reservoirs that are utilized for irrigation of their rice fields that are failing due to prolonged drought. Over several years of similar periodic droughts, they have managed to squeeze out some rains to localized areas impounding water behind dams for irrigation releases, enough to justify to keep trying with this technique. They are extremely poor there, so I don’t think they are wilfully wasting money up a rope doing something for nothing. I realize you need a specific cloud set and humidity to come along that is conducive to artificial cloud seeding, but when it does, there is a hope of getting some much needed precipitation. Utilizing 15-30 micron vacuum packed salts as cloud seed nuclei seeded by a small dual prop airplane. Just a thought…if it worked a few times, might be worth exploring. Anything at this point should be worth taking a closer look at. A few interesting local stories from the cloud seeding efforts in Bohol, Philippines below.

Kent Noonan
November 14, 2018 9:13 am

There has been at least one year recently when early spring rain led to a lot of grass in an otherwise dry summer. I think it was February that rained so hard there was flooding in California, followed by fires.

Reply to  Kent Noonan
November 14, 2018 10:22 am

Yes there was exceptional rain in Feb 2017 which led to the damage to the Oroville spillway (over 12″), most of the dams in that region of Ca filled up and of course lots of grass growth during the following spring. Leads to lots of potential fuel.

Don Healy
November 14, 2018 10:07 am

My research indicates that you will find a high degree of correlation between fuel load and total areas burned. U.S. total timber volumes have increased by over 60% since 1953.

Zack aa
November 14, 2018 10:26 am

My sympathies for Anthony and the community that surrounds him.

NWS shows ytd rainfall totals for Chico 6”, Redding to the north, Sacremento to the south both at 13”. The station data for Paradise being somewhat east at Yarbo Gap at 39” (?)

Thousand Oaks is 7”, Malibu is 10”.

My recollection is since the last rain event in early April ‘18, SF Bay Area has had but one day of trace rain in the subsequent 7 months.

CA ‘16-17 water year anomaly wet, massive fires. ‘17-18 water year anomaly dry, again massive fires.

Steven F
Reply to  Zack aa
November 14, 2018 1:08 pm

“NWS shows ytd rainfall totals for Chico 6”, Redding to the north, Sacremento to the south both at 13”. The station data for Paradise being somewhat east at Yarbo Gap at 39” (?)”

Redding, chico, Sacramento are all at low elevations and in the rain shadow of the coastal mountains. All are in semi dessert environments. Rainfall varies a lot year to year normally in these dry environments.

Yarbo gag is further east in the low Sierra Nevada foot hills. 39″ is probably close to normal for that location. Paradise is further east and higher up so it should normally get a little more rain than Yarbo gap. This amount of rain variability is normal in California.

The wettest locations in the state are coastal and sierra Nevada mountains. in the 2017 /2018 winter snow fall in the mountains was a less than normal but the rainfall was a little above normal. End result was that 2017/2018 winter was about average to little below average. But since everyone focuses on the snow report and weather forcasters, and reporters are calling last winter a drought. It was not.

The current california drought monitor website lists the state at D0 abnormally dry, the lowest drought conditions.
If you look at hte conditions 3 and 4 years ago when we really did have a drought the difference between then and now is dramatic.

Many people don’t simply understand California weather. Unlike the east cost which gets rain fall almost every month of the year with high humidity levels in the summer. California typically gets zero rainfall from jun through September with almost no humidity. May and October are transition months and frequently get no rain but occasional they do. November is typically when the rains really start but it is still not unusual for the rain to start at the end of the month. Currently it looks like we might get rain around thanksgiving. So 7 months without rain is about normal for the state. Unfortunately October and November are typically the months when high winds are common.

Zack aa
Reply to  Steven F
November 14, 2018 9:59 pm

Sorry, I meant Jarbo Gap and ytd precip 35 not 39 inches. Paradise at 1800’. JBGC1 Elevation is listed at 2500 ft, not snow pack level, and the lat long google map for it is east of both Paradise and rte 70 between Pulga and Parkhill. Well within boundaries of the fire.
My point, poorly made, was the fire once ignited burned through areas relatively “drier” at the western Chico end and also 3x “wetter” areas north and east. Longer term drought or no, not my issue, the relevant water year anomaly ending Oct 2018 was between 20% and 25% below normal.

I completely agree that until one lives here it is difficult for an easterner’s mind to fathom the monotony and creeping dessication of our dry season.

Mike Smith
November 14, 2018 10:31 am

Willis: interesting analysis. But here’s a thought… Long periods of drought will cause some trees severe stress. There may be several years of lag before those trees completely die, fall, dry, and provide fuel for a fire.

This leads to the unremarkable conclusion that removing dead trees and vegetation from fire prone areas would be prudent.

For the record, I don’t think temperature or rainfall is driven by CO2!

No Name Guy
November 14, 2018 10:59 am

May to October rain seems limiting. Note that I’m coming from the perspective of a Pacific Crest Trail hiker where winter snow pack combined with its subsequent melt will undoubtedly influence the dryness of the forests, at least in areas subject to snow accumulation or melt runoff. An example was 2017 – a very heavy snow year in the Sierra, with a late melt off (which actually caused fatalities as a couple hikers died trying to cross melt swollen creeks / rivers). High snow plus later melt in a given year would tend, I would suspect, to delay the drying of the forest into fire prone conditions.

Additionally, i suspect there is some lagging effects between precipitation (over an entire water year, October to October) and subsequent fire as the accelerated vegetation growth from a wet year, or series of wet years, doesn’t necessarily burn until following dry year(s). I suspect this effect also applies in areas where the predominate vegetation grows on the annual time scale – a wet winter / spring followed by an abnormally dry summer and fall would result in bad fire conditions that year (sage brush, grasses, manzinita, etc). This would be in contrast to mature forest where I would suspect the pattern would be on longer time scales – at least the following year.

November 14, 2018 11:26 am

As pointed out already it doesn’t rain much in California in the summer and fall so it’s not surprising there’s little or no correlation. I doubt you’ll find a statistical correlation even using winter rainfall totals although it’s obvious that wets years increase the amount of fuel and drought creates higher risk of major wildfires.

From what I’ve read fire was a common occurrence 100+ years ago with areas burning every 15 to 25 years on average. Ancient giant sequoia show this pattern for example. That limited catastrophic fires by reducing fuel load and limiting fuel ladders that enable fire to reach the crown and kill mature trees.

It seems to me that if we knew the average amount of acreage burned annually 100 years ago and compare it to the annual average over the last 25 to 50 years then you could calculate the annual unburned acreage that is building up in the state.

The bottom line is that fires aren’t unusual in California. They’re a part of the natural ecosystem. The issue now is how we protect people and property and manage the urban wildland interface along with managing build up of fuel loads.

November 14, 2018 11:57 am

Willis :
Where is the graph of underbrush in State and National forests?
As I have said on this site before: When the pioneers went to California they had to carry wood for fires as the followed the Platte River across Nebraska as there was no fire wood within miles of the river. Today there is almost a forest along the entire length of the Platte river. The present areas of forest can be confirmed by any internet satellite map service.
As you zoom in you will note that most green areas in NE, UT, WY, KS, etc. are around center pivot irrigation systems. Where are the studies on their impact on rainfall, Temperature, Flora, Fauna, etc.

Go Home
November 14, 2018 12:30 pm

Maybe a comparison of how much acres of prescribed burns, forest thinning, and money spent on forest management would be in order. My guess that they do not do enough and that exacerbates the problem.

kristi silber
Reply to  Go Home
November 14, 2018 1:05 pm

Forest management like that is expensive. It requires access, which can be difficult in mountainous regions. Thinning is not economically viable in some forests, especially if it means removing the material. Prescribed burns require appropriate conditions. Who’s going to pay for it, when state and federal forestry programs are often underfunded as it is?

Go Home
Reply to  kristi silber
November 14, 2018 1:22 pm

Pay me now or pay me later.

Kristi Silber
Reply to  Go Home
November 14, 2018 5:37 pm

Trump’s response to the fire is to threaten to stop all federal funding:

“There is no reason for these massive, deadly and costly forest fires in California except that forest management is so poor. Billions of dollars are given each year, with so many lives lost, all because of gross mismanagement of the forests. Remedy now, or no more Fed payments!”

No reason. Drought has nothing to do with it. And temperature increases associated with climate change have nothing to do with drought. That’s brilliant.

But hey, adaptation is better than prevention! So who cares about a few fires? People will adapt.

Tom Halla
Reply to  Kristi Silber
November 14, 2018 5:41 pm

Kristi, you are being deliberately dense. The threat was contingent, that unless California changed their wildlands policy, the Feds would no longer pay for the consequences of their folly.

Gerald Machnee
Reply to  Kristi Silber
November 15, 2018 12:59 pm

RE Kristi:
**No reason. Drought has nothing to do with it. And temperature increases associated with climate change have nothing to do with drought. That’s brilliant.**
What would be brilliant if Kristi could show that temperatures have increased aka “climate change” aka global warming.
Also it would be brilliant if anyone could fine a scientific study that measures warming caused by CO2.

Kristi Silber
Reply to  Kristi Silber
November 15, 2018 7:39 pm

Tom Halla,

It’s still a threat. Maybe a more appropriate reaction would have been to say, “We are going to review the federal funding for forestry lands in California, and see whether more funds can be shifted to measures which will increase fire prevention and control to keep populated areas safer.” 57 % of forests are owned and managed by the federal gov’t. 40% are owned by private individuals and companies, and native Americans.

Trump assumes that the cause is forest mismanagement. While that may play a role, it’s not the only cause. Besides, CA is doing something about it already.

“Westrup, the governor’s spokesman, pointed to the passage this year of a bill intended to reduce wildland fire danger.

“Under the bill, SB901, the state will dedicate $1 billion over five years to fire-reducing efforts such as clearing brush and setting prescribed burns. It also eases restrictions for clearing drought-killed trees from the state’s forests.

“Brian Price, president of the 30,000-member California Professional Firefighters, called Trump’s first tweet “ill-informed, ill-timed and demeaning to those who are suffering, as well as the men and women on the front lines.”

“At a time when our every effort should be focused on vanquishing the destructive fires and helping the victims, the president has chosen instead to issue an uninformed political threat aimed squarely at the innocent victims of these cataclysmic fires,” Price said in a statement.

“The president’s assertion that California’s forest management policies are to blame for catastrophic wildfire is dangerously wrong,” he added. “Wildfires are sparked and spread not only in forested areas but in populated areas and open fields fueled by parched vegetation, high winds, low humidity and geography.”

Who’s the one that’s dense?

Tom Halla
Reply to  Kristi Silber
November 15, 2018 7:57 pm

If one actually pays attention to what California has done on wildlands management, it mostly rejects controlled burns and logging. Blather about environmental preservation presumes an original state that never existed, as the area has been inhabited since the end of the last ice age, and the Indians definitely practiced active forest and wildlands management.
The environmentalists have the notion that management is “preservation” of something that never existed.

Tom Halla
Reply to  Kristi Silber
November 15, 2018 8:07 pm

On a bit of consideration, I may have been obscure. The fantasy of the environmentalists is that the Americas ever had a stable ecosystem that did not involve active measures by people. As people have been in the Americas since before the ecosystem settled down after the last ice age, there has always been human influence, and purposeful at that. Notably, there have been archaeology studies done in California, that the local tribes maintained as open woodland what became overgrown scrub after becoming a state park, with the interval being a cattle ranch, which had much the same effects as routine fires.

Kristi Silber
Reply to  Kristi Silber
November 15, 2018 7:41 pm

Gerald Machnee,

Kristi Silber
Reply to  Kristi Silber
November 16, 2018 8:14 pm

Tom Halla,

I’m not an environmentalist; it’s always irritated me when people suppose I am one. I agree with you about the influence humans have had on forests. The fire suppression humans have done during the last century has been a huge mistake, in most cases – but in others, it’s necessary; this is a drawback of the formation of permanent settlements in forested areas.

I’m not against logging, but I’m in favor of doing it wisely. There is so much I could say about this, it would probably bore you. Logging is a very important industry in MN, where I live, and I worked on developing a manual for foresters for the DNR.

Forest management for fire prevention is a different thing altogether. It’s costly. Controlled burns can be dangerous, especially in the middle of a drought. Thinning is sometimes counter-productive.

Besides, it’s not just forests that burn.

There is no easy solution, which is why Trump’s remarks were so widely criticized by those who know about wildfire. A better way of looking at the problem is from the side of development and construction. The urban-nature interface has to be more closely examined, and communities have to start seeing wildfire as a potential rather than relying on vegetation management to protect them.

kristi silber
Reply to  Go Home
November 14, 2018 1:11 pm

Besides, forest thinning can actually lead to higher fire risk, since the understory gets more light (which can affect fuel loads as well as drying) and increases wind, which adds to drying.

kristi silber
November 14, 2018 12:53 pm

“But since then, the temperature has greatly underestimated the number of acres burned.

This is clear evidence that the recent large wildfires are not due to the variations in temperature as is widely claimed.”

No, you have given no such evidence. You have only shown that there is not a perfect correlation between temperature and acreage burned. Temperature could still be one of the factors – and if it explains 44% of the variance, that’s no unlikely.

You also didn’t look for a lag time in precipitation’s effects, as others have noted.

Those who look for one or two factors in increased wildfire are not allowing for the fact that fires can have many influences. This is as much an error of those who blame all increase in fire on climate change as those who say climate change isn’t a factor. Willis, your analysis suggests to me that temperature is likely one factor, and it puzzles me that you deny it.

Kristi Silber
Reply to  Willis Eschenbach
November 14, 2018 5:21 pm

I didn’t ask a question, anyway, Willis, I made a comment. Your statistics have interesting results, and it’s weird that you don’t see it. Fine if you have nothing to say in return.

I have just as much right to comment here as anyone else.

Reply to  kristi silber
November 14, 2018 1:46 pm

“your analysis suggests to me that temperature is likely one factor, and it puzzles me that you deny it.”

Realistically, temperature doesn’t have that much to do with it. The key factors are fuel load, oxygen supply and dryness of fuel. I’ve burned large outdoor fires when it was single digits and when it was 90F, and they burn the same. Fire affects the local temperature, more than vice versa. There’s actually more oxygen in cooler air. If you want a really hot open fire you add oxygen, not heat.

Kristi Silber
Reply to  icisil
November 14, 2018 5:24 pm


Temperature has an effect on drought and moisture in the vegetation.

Russell Robles-Thome
November 14, 2018 12:57 pm

Willis –

Temperature and Acres Burnt are both rising, so I believe there will necessarily be a correlation between them, even if they are unrelated phenomena. I think you need to de-trend both series first before doing the correlation analysis.

Russell Robles-Thome
Reply to  Willis Eschenbach
November 15, 2018 1:49 am

Reassuring, thanks for the response! R.

November 14, 2018 1:05 pm

My thought is that there may be a correlation with the combination of spring rain and length of summer/fall drought.

November 14, 2018 1:28 pm

As others have pointed out, May-October rainfall in CA is insignificant to the calculations, as it insignificant in itself. The wet season is in the wintertime, and if rains are abundant, forest fire numbers will be vastly reduced for the following year, as the moisture resides in the soil and vegetation. Where has every one been for the last `seven years? California has been in a severe drought (except for 2015/6-17), making the forests a tinderbox. During winter 2015-17 Northern-Mid CA had heavy rainfall but not the Southern part which was still stuck in drought conditions–just as they are now, and the South had massive fires in 2016-currently. No matter how important sensible wood clearing is, that is not the main problem.

In parts of Europe, there are no forest fires because the weather system is very dynamic with regular wet/dry cycles (daily, monthly, yearly); the atmosphere is very healthy–blue, lack of “smog”, and does not suffer from dry seasons nor drought. One cannot even start a forest fire if one tried as the trees are full of sap and water. One can burn yard trimmings during winter season without prohibition, and I have seen one of these fires “over jump” its area and begin to smolder the surrounding bushes. It sizzled for a while and then went out because the bushes were too moist inside.

In summary, it is not land management, nor hypothetical global-warming, which feeds these fires, but the lack of a healthy weather system which naturally provides moisture by dew, humidity, and rain.

Kristi Silber
Reply to  al
November 14, 2018 5:48 pm


It’s not global warming, but lack of a “healthy weather system”? Are you aware that dry areas getting drier is exactly what is predicted by global warming? And that temperatures are part of drought?

It’s not “hypothetical” global warming, no. It’s actually global warming, regionally expressed in CA, as Willis’s data show.

It’s striking that people will use such convoluted reasoning to deny that climate change has anything to do with wildfire. It’s not the whole story, but it can’t be eliminated as a factor.

Reply to  Kristi Silber
November 15, 2018 1:17 am

“Dry areas getting dryer have been predicted by GW?” Of course, doomsday scenarios have been the mainstay of Global cooling/warming/change since its inception. Just one favor Kristi, please step outside in Houston with your Fall clothes and wake up to reality!

November 14, 2018 1:31 pm

PG&E loses 25% of market value today alone with concerns on causing #campfire Paradise fire. PCG closing price today 25.59 USD, down −$7.13 today on a volume of 52 million shares. Stock price had a year to date high of about $55.63 a year ago and as recent as recent as Nov 7/18, down from about $48.80. Bonds are crashing as well, with the possibility of a bankruptcy. Facing $17.3 Billion in claims for 2017 fire season. Assuming even higher for 2018, especially if #campfire is deemed to have been started by PG&E.

Seeking state intervention and aid for billions in a possible bail out scenario if claims exceed insurance payouts. Market seems to be pricing in a guilty verdict already. Big, big troubles for PG&E. And should be for the Governor’s office as well, but I doubt anything will happen on that front.

November 14, 2018 1:50 pm

My thoughts go out to all in Ca affected by this tragedy.

The devastating bushfires in Victoria, Australia, in 2009 burned over 1 million acres in a few days, based on about seven major fires throughout the state (more than 300 individual fires). The weather was a contributing factor on with the main day of destruction with 47 degC temperatures (115 degF) and 90km/hr winds (56 miles/hr) winds. 180 people lost their life and many more were injured. Whole towns were wiped out.

The ignition causes of the fires were determined to be a variety of things : power line arcing, stupid use of machinery, some lightning and would you believe it, arson.

But the underlying cause of the severity of the fires is believed to be years of failure to clear forest fuel loads through controlled “cool burns” in winter, especially on government controlled land, and inappropriate housing developments in heavily wooded areas. Recent changes in several local council regulations stopping general fire safety practices such as clearing trees or bush on private land (mainly due to green ideology) was also a factor, and many regulations were changed back after the tragedy. The importance of fire breaks in forests and cleared zones around houses was also identified to be a significant factor in fire control and limiting damage.

The 2009 tragedy was a wake up call for Victorians that resulted in changed regulation and fire safety preparation. But Victoria has major fires every few decades, (1939, Ash Wednesday 1983, 2009) so we just wait for the next one.

Joe G
November 14, 2018 3:24 pm

Which is less expensive:

1) Laying out miles and miles of irrigation tubing and sprinkler systems throughout the forests to keep them moist- or some kind of plan, even flying over and dropping water before the fires start

2) Annual fires that destroy complete towns and thousands of acres of trees?

John Dilks
Reply to  Joe G
November 14, 2018 8:44 pm

Joe G.
1. California does not have the water available to irrigate the forests. They barely have enough water for humans.
2. Trees grow back after fires. Towns need to protect themselves with cleared areas surrounding them.

Kristi Silber
November 14, 2018 6:05 pm

“Rohde compared the rainfall and temperature records and highlighted the largest fires. However, this gives only a few data points. I wanted a larger view of the situation.”

A “few data points”? Since 1895, 9 of the top ten largest, and 9 of the top ten most destructive fires have been since 2000.

There are way more than a few data points here. There are two really interesting graphics – people should take a look if they haven’t already.

Steven Mosher
November 14, 2018 7:49 pm

Looking for the data source for acres burned

usually willis includes his data.

I did find this WARNING about using the data

‘Due to the changes in data
collection, methods, and systems over the years, information may not always
be comparable and data may be of differing accuracy or completeness.”

Looking at these reports it is unclear what figures Willis used.

I will note after reading some of these reports that they often warn

due to the hot and dry weather…… we got a lot of burning

My suspicion is that linear regression is not the best way to go at this.

I have some thoughts, if Willis has the acreage burned data for show an tell

Steven Mosher
November 14, 2018 7:56 pm



‘CAL FIRE’s firefighters, fire engines and aircraft respond to an average of 5,400 wildland fires and answer nearly 192,000 calls for other emergencies each year. During 2007 CAL FIRE responded to 3,610 wildfires within its Direct Protection Area. This represents a decrease of 33% below last year and 33% below the 5-year average. These fires burned 434,667 acres which is 49% above last year and 54% above the 5-year average. Up until October, California fire season had been relatively light. Seasonable conditions were seen throughout the state through the middle of October.

That all changed as forecasters predicted a strong off shore flow beginning October 21, 2007. CAL FIRE and other fire departments began to preposition staff and fire equipment throughout Southern California. On October 21st, numerous wildfires sparked across Southern California. With the combination of strong winds, low humidity and dry conditions, the situation was set for a disaster. Fueled by dry vegetation and strong Santa Ana Winds, firefighters battled several raging infernos. Nearly one million residents were evacuated. This was the largest mass evacuation in California history. Ten people lost their lives and over 510,000 acres were charred from the fire siege. The last of the raging wildfires were not fully contained until early November, 2007.”

yes, it seems these fire fighters know nothing about the relationship between hot, dry, offshore flow
and fire.

Bottom line. If you regression is not showing a relationship between hot and dry and worse fires

A) you regression or data is missing something OR
B) fire fighters dont know jack

Steven Mosher
Reply to  Willis Eschenbach
November 15, 2018 6:10 am

I would not say we have no evidence.

in fact the evidence is in your residuals

First things. Linear regression is probably the wrong tool. One reason why is the variables
may have thresholds. For example, if 2.45 inches of rain or more is enough to depress a fire season somewhat you may not see a linear response difference between say 3 and 4 inches or between 4 and 5 inches.. wet may be a threshhold

Same with temperature. there may be threshholds

So rather than just assume a linear model ( although doing one first should show you what
you miss) you can do a nonparametric recurvsive partitioning model.
basically tree regression. There are many options in the machine learning space, I like ctree
random forest is another option, meh.

Anyway, go ahead an plot your lm(Acres ~temperature) and plot it. Pretty sure you did
Pretty sure you saw what I see. those few points that stick out over 1m acres burned? are they dry?

Any way, in the tree regression this becomes pretty clear

A simple partioning regression against temperature shows 3 distinct temperature categories

=68.4 & =69.1

Essentially the tree regression will tell you to use these categories of temperatures
as your predictor…

Your R^2 will increase and your model will be a better predictor. You can think of it this way
Any value between 68.4 and 69.1 is going to predict the same acreage burned.

Moving to 4 categories you can get a little bit better prediction, (r^2 .53 ) but what I see from three categories and the residuals from the simple linear regression tells the story.

When you do a tree regression you will see a few outliers in every prediction interval.
confirming the story

The outliers are typically drier years.

In short, the problem is you have evidence of the dry years being more problematic
in every temperature category, but there are very few data points, so in a linear regression
this information just looks like noise/outliers. Of course, you can just call them outliers
and say they mean nothing, or you could look at the outliers and ask what they teach you

in the 70 or so years you have there basically isnt enough data of dry years to influence the simple regression.. put another way.. the hot dry years have more fires than your model predicts.

Same data, different way of interpreting it.

Outliers sometime have signal

Steven Mosher
Reply to  Steven Mosher
November 15, 2018 6:27 am

I would not say we have no evidence.

in fact the evidence is in your residuals

First things. Linear regression is probably the wrong tool. One reason why is the variables
may have thresholds. For example, if 2.45 inches of rain or more is enough to depress a fire season somewhat you may not see a linear response difference between say 3 and 4 inches or between 4 and 5 inches.. wet may be a threshhold

Same with temperature. there may be threshholds

So rather than just assume a linear model ( although doing one first should show you what
you miss) you can do a nonparametric recurvsive partitioning model.
basically tree regression. There are many options in the machine learning space, I like ctree
random forest is another option, meh.

Anyway, go ahead an plot your lm(Acres ~temperature) and plot it. Pretty sure you did
Pretty sure you saw what I see. those few points that stick out over 1m acres burned? are they dry?

Any way, in the tree regression this becomes pretty clear

A simple partioning regression against temperature shows 3 distinct temperature categories

=68.4 & =69.1

Essentially the tree regression will tell you to use these categories of temperatures
as your predictor…

Your R^2 will increase and your model will be a better predictor. You can think of it this way
Any value between 68.4 and 69.1 is going to predict the same acreage burned.

Moving to 4 categories you can get a little bit better prediction, (r^2 .53 ) but what I see from three categories and the residuals from the simple linear regression tells the story.

When you do a tree regression you will see a few outliers in every prediction interval.
confirming the story

The outliers are typically drier years.

In short, the problem is you have evidence of the dry years being more problematic
in every temperature category, but there are very few data points, so in a linear regression
this information just looks like noise/outliers. Of course, you can just call them outliers
and say they mean nothing, or you could look at the outliers and ask what they teach you

in the 70 or so years you have there basically isnt enough data of dry years to influence the simple regression.. put another way.. the hot dry years have more fires than your model predicts.

Same data, different way of interpreting it.

Outliers sometime have signal

ah shit temperature ranges got screwed up

Kristi Silber
Reply to  Steven Mosher
November 15, 2018 8:01 pm

Steven Mosher,

Am I missing something? Does Willis’s analysis not show that 44% of the variance of acres burned is explained by temperature, and a very low p-value? To me that seems like a pretty good signal, considering all the other factors that come into play.

Rohde’s graphics are pretty impressive, too. It’s not a statistical analysis, but it’s suggestive of a relationship between climate change and fire size/destructiveness.

The issue of precipitation is more complex than looking at total summer rain vs. acres burned, as others have pointed out. Winter precipitation is important, either for drought or for fuel load. Long-term drought is also a potential factor. So it’s no surprise that part of the analysis wasn’t significant. Willlis is right that he found no evidence for a link between precipitation and acreage burned, but that doesn’t mean there isn’t a link.

Steven Mosher
November 14, 2018 8:09 pm

More interesting things on acres burned

Willis you gave the source but looking at that source I am wonder what figures you took from the documents

Only cal fire? or other agencies as well?

Ivan Kinsman
November 14, 2018 10:40 pm

All US sceptics should read the NYT’s updates on climate change abd its impact on California’s inceasing numbers and more extreme wildfires. As more events like the Camp fire occur, the more the mainstream American public will require action from their government to reduce co2 emissions. Less CO2 = less extreme wildfires = less acreage burnt.

Gerald Machnee
Reply to  Ivan Kinsman
November 15, 2018 1:10 pm

RE Ivan:
**As more events like the Camp fire occur, the more the mainstream American public will require action from their government to reduce co2 emissions. Less CO2 = less extreme wildfires = less acreage burnt.**

Sure, all skeptics AND CAGW types should look up and find me proof that more CO2 gives more extreme wildfires. As well all CAGW types should find me a scientific study that proves CO2 causes global warming aka climate change.

Kristi Silber
Reply to  Willis Eschenbach
November 16, 2018 6:44 pm


I hope you will read this. I don’t expect to engage you in conversation.

Climate changes regionally. The prediction is that in general, dry areas will become drier and wet areas will become wetter. This is somewhat borne out by the evidence of U.S. patterns. – Figure 3

If incidence of wildfire is related to precipitation, you would not necessarily expect a national increasing trend in acreage burned.

Quite apart from that is the fact that there are so many complicating factors, such as vegetation history and management, development patterns, presence of ignition sources such as electrical faults, etc. This is why I find your analysis so striking – there does seem to me to be a relationship between temperature and acreage burned. I don’t know why you find it offensive that I point this out.

While I understand Mosh’s point about thresholds, I’m not sure that’s the best way to look at this. For one thing, different vegetation (and forest) types are likely to have different thresholds. Another is that the precipitation over the course of years could have a large impact on tree health. If a forest has gone though 5 years of drought then has one rainy spring, that may not be enough to make up for the long-term stress, which can make trees more susceptible to disease and insect damage (in some areas – Yosemite, for instance – insects are responsible for a lot of dead and dying trees). Extreme precipitation events, the kind that quickly fill reservoirs, may not help that much, especially on hillsides where much of the rain flows above ground. A cold early winter with delayed snow, followed by an early spring melt could cause much of the water to run off over frozen ground. Assessing effects of precipitation on vegetation drought status is not at all straightforward…but temperature is definitely a significant factor.

We all have different views, Willis. I support the idea of AGW and believe it will come at a net cost, though it’s uncertain just how high it will be. There is much we don’t know about how the natural world will respond. This isn’t an environmentalist perspective, it’s a recognition of the fact that human welfare is dependent on the state of the natural world – the CA fires are a good example.

I’m not a hard-liner about policy. I recognize that there are economic and social factors that have to be taken into account. I think it’s more important to slow the rate of change than to limit it, allowing people and the biota time to adapt. This is why I believe doing something is better than doing nothing.

In CA, the most important thing to do will be to develop a plan in order to prioritize use of limited resources and engage the public. Wise development and home construction are essential (using fiber cement siding rather than wood, for example). Whether or not climate change is contributing to increasingly damaging fires, people have to adapt. Forest management is only one part of the picture.

I make mistakes, but I’m not stupid. I don’t whine.

Kristi Silber
Reply to  Willis Eschenbach
November 17, 2018 7:29 pm

Yeah, I realized I’d wasted my time as soon as I’d posted. I should know better.

November 15, 2018 11:02 am

“Is the California Drought a symptom of long term climate change?
The current drought is not part of a long-term change in California precipitation, which exhibits no appreciable trend since 1895.”

Kristi Silber
Reply to  peterhodges
November 16, 2018 7:10 pm


“The current drought, though extreme, is not outside the range of California hydro-climate variability and similar events have occurred before. Although there has been a drying trend in California since the late 1970s, when considering the full observational record since 1895, there is no appreciable trend to either wetter or drier California winters.”

This is a general pattern. Most of the climate change attributable to CO2 has appeared since the late 1970s. This is because before then other factors have played more of a role, particularly solar irradiance and aerosols.

Robert Bissett
November 15, 2018 12:53 pm

PREDICTION: Devastating fires will happen again and again in California and elsewhere. Wooden houses and their contents will be tragically lost, not to mention lives. The survivors will regroup and rebuild. Inexplicably, they will reproduce the same highly flamable structures as before using insurance money. Contractors are happy to build wood frame houses because it is cheap and they have it down to a science. Permitting authorities are happy because the codes and regulations allow it. Insurance companies are happy because when customers are living in fear of the next fire insurance makes a lot of sense. I don’t know if we can put an end to wild fires, but I know we can put an end to houses burning down. A wood frame house in a fire-prone area is little better than a bonfire waiting for a spark. Fire proof houses can and should be built in those areas. Do a search for “John Davis and Lorrie Brown” for one example from last year that withstood a major fire in California. Monolithic domes, concrete and steel, have survived fires as well. Normal looking houses can be built with concrete, walls and roof. Even so, very few will do anything like this. True, it may cost a bit more. What does it cost to rebuild your entire house? What price do you put on your belongings and memorabilia? What is the emotional price for the loss of your home? Evacuation may still be necessary, but you should have a place to go back to. Permitting authorities could require fireproof houses where needed. Insurance companies could decline to sell insurance for houses in danger from fire. The media could inform the public. I’m not optimistic that anything will be done. (rant over.)

Robert Bissett
November 15, 2018 1:07 pm

Found another one: search for “Architect Eric Lloyd Wright” to see a video from 2007…concrete and steel is fireproof.

November 16, 2018 7:11 am

@ Willis Eschenbach,

please read “Influence of wildfire induced land-cover changes on clouds and precipitation in Interior Alaska — A case study” (Atmospheric Research 84 (2007) 142–168) authored by Moelders and me.

November 16, 2018 7:19 am

The acres burned has a lower bound near 0 while the temperature effectively does not have a lower bound (technically it does have a lower bound, but given how far you are above that bound you can treat the data as a random Gaussian distribution). I have found this messes up my analyses frequently. You might try taking the log of the acres burned.
In a post-hoc hand waving argument you could say something like: “The western United States is in a disequilibrium between low burn and high burn states. Each temperature rise will also raise the probability of continuing a burn linearly. However, as the probability increases the number of acres burned will not increase linearly. The number of fires started will increase linearly and the probability of sustaining a fire increase linearly, but more fires will cause more incidents that could be sustained. Blah blah blah and here is a monte carlo simulation…”
But in all reality, I think the log of the acres burned will give you a much better match. The problem is that the units are almost impossible to understand (log acres per degree C, seriously?).

November 16, 2018 11:37 am

@ willis
I posted this a little bit ago, but it hasn’t shown up. I apologize if it posts twice.
I forget the name of the model, but it would be a checkerboard type model. Each square would have a probability of sustaining a wildfire, with the probability drawn randomly from a distribution model. As the temperature increases the mean of the probability distribution would increase. Then you seed fires and check the spread. The interesting thing about a model like this is that as you increase the mean the area affected would increase non-linearly.
I learned this model when studying the efficacy of radiation therapy on cancer treatment. I think it would have an application to this space. The model itself would be entirely linear (all that moves is the distribution center), but the effects are non-linear. The radiation model was a linear probability model but demonstrated why a ghastly amount of radiation was required to make it likely to kill that last cancer cell. The model was linear, but the effect was non-linear (I believe it was logarithmic).

Johann Wundersamer
November 22, 2018 7:01 am

What a year, Iceland low and Azores high.
Pollen dust and red Sahara sand.

From dormouse day to dormouse day.

Mark in calendars!

Johann Wundersamer
November 22, 2018 7:11 am

What a year 2018,

Iceland low and Azores high wandered.

Pollen dust and red Sahara sand.

Heavy rains and hailstorms in the EU.

The new normal.

From dormouse day to dormouse day.

Mark in calendars!

See ya 2019.

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