Fire in the forest, dry grass and trees are burning

Increased Wildfire Danger over the Western U.S. from Wet and Cold Conditions

From the Cliff Mass Weather Blog

There is an enhanced potential for wildfires over the western U.S. this coming summer and early fall, but it is not due to warming and drying.

In fact, just the opposite.   A cool, wet winter has created an increased wildfire threat by producing a bountiful volume of flammable grasses. 

A threat that extends from eastern Washington into southern California.

Eastern Washington Near Thorp, WA, July 2022

When most people think of wildfires they usually refer to forest fires.  However, grass fires are just as important in the West, if not more so.  Furthermore, burning grass plays an important role in many forest fires. 

Many of the most damaging fires in the western U.S. have had a large grass contribution.  For example, the eastern Washington town of Malden, which was destroyed in September 2020, and the 2018 Camp Fire around Paradise, CA.

The distribution of seasonal grasses in the West is shown below (indicated by green colors).  There is a LOT of grasslands across eastern WA and OR, and over central and southern California.  And many of the forest areas have an understory that includes grasses and other seasonal vegetation.

The western U.S. has a Mediterranean climate, with winter precipitation and dry summers (yes, this includes Washington State).   Precipitation during the winter encourages seasonal grass growth and is followed by a summer warm/dry period, resulting in substantial flammable fuels by mid-summer.  All that is needed is an ignition source and strong winds, which result in rapid fire spread.

Research studies indicate that precipitation is most critical around November (which supports germination and early growth) and in March/April (which provides moisture as the strengthening sun encourages rapid plant growth).

Interestingly, western grasslands and rangeland have become much more flammable over time, as explosively flammable, non-native grasses such as cheatgrass have spread around the West.  This is NOT due to global warming.  And there are far more sources of ignition these days, including huge increases in electrical infrastructure and population at the urban/wildland interface.

To get an intuitive idea of how important grass fires are, here are maps of historical fire locations for central CA.  Lots of large fires away from the forested mountains.  Importantly, extensive grass near and within forested slopes can play a major role in initiating and spreading wildfires.

Numerous and extensive wildfires have also been found in grassland areas around eastern Washington State (see below).

The Situation This Year

The percent of normal precipitation during the present water year (from Oct 1 to now) is shown below. Most of California was wetter than normal as was southeast Oregon and the eastern slopes of the Cascades.  Surprised that the Cascade easterly slopes were moist?  Blame the easterly, offshore-directed flow that made the rest of the region dry!

Importantly, higher than normal precipitation has continued during the critical last month over California, Oregon, and yes, the eastern Cascade slopes.

All this moisture has encouraged luxuriant grassland growth around the West.   

Do you want to see some proof?

Below are two NASA MODIS satellite images for southern California: the first is for today and the second is from two years ago (2022), also on April 21.  

Look closely.  A LOT more green today.    When that stuff dries out….as it WILL dry out…. there is potential danger.

But let us get more quantitative about the wildfire threat.  

A wonderful USDA website called uses precipitation and other data, manipulated using machine learning, to predict the dead fuel load (mainly dead grasses) later this summer (see below).   As noted by grassland/range expert, Dr. Matt Reeves, when the standing dead fuel load gets to about 800 pounds per acre, the wildfire threat is substantial.  

As evident below, substantial portions of eastern Washington, eastern Oregon and particularly California will reach that level.

The bottom line:  there is a substantial grass/rangeland wildfire threat this summer after the West dries out, as it always does.

There is a lot of talk in the media and others that wildfires in the West are mainly the result of heating and drying due to global warming.   The truth is perhaps a bit more nuanced and complicated.  Cool and wet winters and early spring can greatly increase wildfire threats.


The Northwest Weather Workshop agenda and information are online.  If you want to attend you must register (on the website).   A few speaking slots are still open for those interested in presenting.

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April 23, 2023 2:58 am

This is absolutely normal variation. Yeah, they ring alarm bells every wet winter. March like weather cool and wet wise in western MT this April. Been here 45 years, every year has it’s little anomalies. The constant “climate change” pimping from idiots gets old and lame as f**k. And I worked in timber harvesting, when you spend 8-12 hours a day you pay attention to the weather.
If you want to shut someone up about how the recent forest fires are so bad tell them about the 1910 Burn. It blew up to 4 million acres in a couple days and burned from the St. Joe to Canada. Then ask them what the “climate” was like then as that fire was bigger than anything recently by a factor of 10. ’88 and ’94 were big years as well. I’ve worked most of the area and it is enormous.

Reply to  missoulamike
April 23, 2023 2:59 am

8 to 12 hours outside

Joseph Zorzin
Reply to  missoulamike
April 23, 2023 6:08 am

“And I worked in timber harvesting, when you spend 8-12 hours a day you pay attention to the weather.”

Excellent! I’ve been a field forester for 50 years. Timber harvesters have a bad reputation. There are few bad apples out there in the business but most are very hard working people- the work is very dangerous-and few earn more than an average blue collar income. They also have more common sense than most doctors, lawyers and teachers that I’ve known. You have to or you can’t survive in the woods for long- unless in a government job. 🙂 And they certainly have a better understanding of the climate than 97% of climate “scientists”.

Reply to  missoulamike
April 23, 2023 6:14 am

Yeah, well, umm, the sky is still falling according to the climate cult due to “man”. If you continue to point out that the weather changes are really no big deal, how do you expect them to collect more money from the rubes? Personally, I’d like to see the climate cultists leave the planet and bother some other galaxy or something. Maybe, its’ just me.

Reply to  missoulamike
April 23, 2023 6:41 am

Cool and wet in Colorado too. In warmer years I had a decent part of my garden planted already. The next 10 days look similarly cold, so I’ll reassess later.

John Shewchuk
April 23, 2023 3:14 am

In just 26 seconds, proof, more than 90% of wildfires are man-made …

Hoyt Clagwell
Reply to  John Shewchuk
April 23, 2023 9:26 pm

Better to show a map of the West’s homeless encampments. That’s where most of the fires in California start. That and controlled burns that aren’t so well controlled.

Ron Long
April 23, 2023 3:25 am

Good report from Cliff Mass. As a Geologist who has worked and camped extensively in northern Nevada, I am aware of the cheatgrass (an imported variety of tall grass which dries out too much for cows to eat in the summer) risk when there is a wet late winter or early spring. Our rule is “don’t drive into a dead-end canyon with a following wind and thunderstorm activity in the area”. For a look at the cheatgrass fires look at Google Earth ™ at northern Nevada coords: 41deg 32′ 26.8″ N and 116 deg 43′ 39.3″ W. The trace of cheatgrass fires is readily visible. For sure these events are common and not increasing.

Joseph Zorzin
Reply to  Ron Long
April 23, 2023 6:10 am

I wonder if any effort is being made to reduce the abundance of cheatgrass.

Beta Blocker
Reply to  Joseph Zorzin
April 23, 2023 7:20 am

Thirty years of research has been done at Washington State University on ways of controlling cheatgrass. There has been some success at keeping it off of small plots of land, but not on the larger western range lands.

Cheatgrass is otherwise known as grassoline. If it burns off in a major range fire, it’s back again as thick as ever two years later, ready for the next big burn cycle.

Reply to  Beta Blocker
April 23, 2023 7:41 am

“Cheatgrass is otherwise known as grassoline. If it burns off in a major range fire, it’s back again as thick as ever two years later, ready for the next big burn cycle.”

Which increases the atmospheric CO2 fertilizer for future flora to flourish.

April 23, 2023 4:26 am

Increased Wildfire Danger.

The weather [in the UK at least] rarely ignites a fire, people do it all the time.

“Disposable barbecues must be banned in England, says fire chief” – Grauniad
“London Fire Brigade (LFB) said there had been a spike in e-bike and e-scooter fires in London “ – BBC
“Every match or lighter can start a fire so please follow this advice to reduce chances of having a fire caused by matches or lighters. “ – Cheshire Fire and Rescue Service 

But it isn’t just the ignoramii. But then what do we call post-modern [unhinged] academics?

“California Professor Accused Of ‘Arson-Setting Spree’ Charged With Starting Wildfire

A California criminal justice professor is accused of intentionally setting an arson wildfire in Northern California next to the state’s massive Dixie Fire.” – Daily Wire

Traditional practices of burning moorland and cutting peat are very much verboten – two indigenous practices that are no longer hallowed….

Ron Long
Reply to  strativarius
April 23, 2023 5:19 am

You put your finger on a growing menace, the self-rightous arsonist who somehow believes they are saving the planet by setting it on fire.

Reply to  Ron Long
April 23, 2023 5:22 am

A classic case of burning the village to save the village.

Joseph Zorzin
Reply to  strativarius
April 23, 2023 6:13 am

destroy the planet to save the planet

Joseph Zorzin
Reply to  strativarius
April 23, 2023 6:12 am

Just curious- if moorland isn’t burned, does it revert to forest?

Reply to  Joseph Zorzin
April 23, 2023 6:26 am

Well, as I understand it; moorland can support specialist wildlife and can form mosaics with other open and wooded habitats. Moorlands and heaths are characterised by their lack of trees – that’s a climate related thing

Last edited 1 month ago by strativarius
Frank from NoVA
Reply to  Joseph Zorzin
April 23, 2023 9:54 am

Where we live in NE, the upland ‘progression’ seems to be pre-colonial forest => marginal colonial farm land => abandoned farm land / second growth woods => beaver ponds => dead trees.

Joseph Zorzin
Reply to  Frank from NoVA
April 23, 2023 11:59 am

It is quite complex. I’ve been bushwhacking the forests here for exactly 50 years. The second growth is now in some places 3rd or 4th generation. Some of the forests has been badly abused (high graded) though much is well managed. Much is locked up and now there is a movement here to lock up all the forests “to save the planet”. The concept is called “proforestation”. My attitude towards it can only be described as vehement. The greens in MA are now pretty much oppossed to industrial scale solar “farms” because most would be built in forests- that is clearcut forests. They want green energy but want to save the forests. And by save they also mean save from those horrible forestry folks!

Joseph Zorzin
April 23, 2023 6:02 am

“non-native grasses such as cheatgrass have spread around the West. This is NOT due to global warming.”

here in the American northeast we now have a lot of invasive species- whenever I read about them in any media- the problem is always blamed on climate change- when in fact, most of these species came from other continents in recent times either brought here purposefully or they got here on freight or other means

April 23, 2023 6:11 am

If there is any truth to this at all they should be doing controlled burns NOW, not once everything dries out. Get the convicts out there and put their asses to work.

Howard West
April 23, 2023 7:19 am

That is why need more cattle, sheep and goats on these areas. However, their people who are in control that will use this “PROBLEM” to further restrict access. they would rather have the grass lands BURN that to add meat to our food supply.

Reply to  Howard West
April 23, 2023 8:25 am

I would suggest only the cattle. It’s hard to top grain-fed beef ribeye. 😋

Peta of Newark
April 23, 2023 7:36 am

Ain’t they just soooo very gorgeous….

The alert viewer will notice how the place is *not* on fire in that video nor does appear to have been recently….

April 23, 2023 8:30 am

This is what I mean by “climate same” (as opposed to climate change). The western sides of continents at those latitudes tend to have Mediterranean climates with wet winters and dry, sometimes hot summers. California, Iberia and Morocco, over to Israel (Eurasia is really one super-continent), Western Australia, and so on. Let me know when Los Angeles becomes a rain forest, then maybe we can talk about climate change…

Erik Magnuson
April 23, 2023 11:36 am

My experience with southern California is that the major fire seasons occur the year after a dramatically wet rain season. A couple of examples: 1968-69 was a very wet season, Laguna fire was fall 1970, 2005-06 was a wet season with major fires in fall of 2007.

I’d also wonder if increased CO2 is a contributing factor as the world is becoming greener.

Reply to  Erik Magnuson
April 23, 2023 2:40 pm

Well the greener world does appear to be associated with the increasing CO2 so you may have a point here, but it’s nothing alarming or actionable through draconian govt edicts.

April 23, 2023 1:09 pm

No worries, the Leftist-marxist democrats will lie about it as they always do to their naive/scientifically illiterate base.

April 23, 2023 2:08 pm

Very informative.

April 28, 2023 7:24 pm

Log it, graze it, or watch it burn…

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