NOAA Confirm Heatwaves Are Declining In California


OCTOBER 8, 2020tags: california

By Paul Homewood

I have often published official graphs of individual stations, which show that heatwaves in California were more intense in the past. These run contra to NOAA’s official temperature record shown above.

NOAA themselves, however, a summary of climate trends in California a few years ago, which backs up my station data:


Below is the relevant table:


Not only do the 1930s stand out for heatwaves, but the last decade appears to be little different some of the other periods in between.

The exercise only takes us up to 2014, but my analysis does not suggest anything untoward happening in the last five years. If heatwaves really are getting worse because of global warming, we would surely have seen a steady trend upwards in the number of extremely hot days during the last several decades.

We can compare this state graph with a similar one for Lemon Cove showing number of days over 100F:


The pattern is similar, with heatwaves peaking in the 1930s, followed by a much colder interlude between the 1960s and 80s.

The two years of 2017 and 2018 stand out, but other than that heatwaves at Lemon Cove since 2000 appear to have been around 1940s and 50s levels.

NOAA’s maximum temperature graph is obviously averaged over the whole of the summer, so won’t necessarily reflect the heatwave patterns, It may be that there a fewer unusually cold summer days now, unlikely though that may seem.

NOAA’s graph of extremely hot days does however pose more questions about the reliability and accuracy of their monthly temperature records, both for California and the US as a whole.

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mario lento
October 9, 2020 3:57 pm

This nice article will be banned from Facebook now that we are close to the election.

Robert of Texas
October 9, 2020 4:19 pm

One can have fewer hot days in a month or season, and still the average goes up if there are a lot of “warmer days”. This would likely support the hypothesis that Urban Heat Island effect is more pronounced – that is recording stations are recording more and more heat pollution from nearby human changes like more people, more buildings, and more air conditioning.

Without a good understanding of UHI, the temperature measurements are pretty much useless. If you have people in the right places who are hell-bent on a belief in AGW, then this will never be fixed as it undermines their faith. They have turned so-called scientific measurements into propaganda.

Reply to  Robert of Texas
October 9, 2020 5:16 pm

I think the modification of hydrology is under appreciated in and around cities. When you have large areas of the surface that do not absorb rainfall and areas that funnel the rainfall into catchbasins and into rivers, etc. you have a much lower degree of evaporative cooling. In a major city, pretty much 100% of all rainfall is not available to that effect. I estimate that where I live in the burbs, probably 33% or more land surface cannot absorb water and a good 10% shunts it directly out of the area. Even with a “properly sited” station, this has to raise the measured temperature.

Reply to  shrnfr
October 9, 2020 6:03 pm

Heat… by itself… does NOT ignite fires. It takes lightning, power line sparks or arson (including accidental arson) to ignite dry brush. Rake the damn forests. Get rid of the dead fuel. Also create cleared areas to prevent spread… like they do in EU.

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Michael Jankowski
Reply to  shrnfr
October 10, 2020 12:37 pm

Very true, shrnfr.

IPCC and climate science are only concerned with hydrology related to extreme weather, drought, and floods, though.

Reply to  Robert of Texas
October 9, 2020 6:11 pm

Night time temperature maybe cause mores stress on the body as less time to recover for the next day.
UHI is dominant at nighttime.
Shorter life span, less concrete and steal, and larger property sizes.
Longer life span more concrete and steel and more dense living. But more aircon.

I think it’s still fair to say more elderly would die today from the same heatwave.
But it’s for the alarmists to prove otherwise.

Reply to  Robert of Texas
October 10, 2020 3:42 am

I live in Melbourne Australia, 7km (4.5miles) from the CBD. I used to drive though the city and out into the badlands for work. Routinely, the temperature close to the CBD was 2C (3.5F) warmer than either the badlands (30km out) or my house (7km out) winter or summer. Decades ago, I lived in Moscow for a year. In spring, Moscow central was snow and ice free, but out in the burbs, you could still ski. Anyone who thinks UHI is a denier myth is denying reality. Millions of tons of high heat capacity/retention concrete and asphalt can’t be wrong.

October 9, 2020 4:33 pm

Sorry – off topic But it looks like Hurricane Delta came ashore as a category 1 hurricane. Top sustained winds max so far have been 77 mph.


October 9, 2020 4:35 pm

How come they haven’t adjusted away the heat that dominated the thirties like the Australian BOM has done.?We lost our Guinness book of records hottest day in Marble Bar by such adjustments.

October 9, 2020 4:38 pm

Tony Heller researched the temps of the 1930s and there is a cluster of most days over 95F…most days over 100F…over 105F….over 110F for the entire country. If you want to use statistics, this is the type of data you want….there is always some place on earth that sets a new high or low temp every year but it is not very meaningful for the entire planet. I am not an expert on statistics but I suspect that one temp station per state that has a history of not having an urban island built around it would suffice for the whole country if data for decades is used. We don’t have the data or a couple of remote islands….one in the Pacific and one in the Atlantic, but if we did….I believe 2 temp stations would suffice for global temp.

Reply to  T.C. Clark
October 9, 2020 5:15 pm

I do not understand this reasoning. States can vary in temp by 10 or more degrees F at any point in time. For example, the Piedmont of NC vs. it’s mountain areas.

Reply to  icisil
October 9, 2020 5:42 pm

In regard to global warming or cooling…it is the temp change over years ..decades…centuries that matters. If the temp is changing, then sooner or later it will register on remote islands like Pitcairn in the Pacific and Tristan da Cunha in the Atlantic where no man made structures or activities could affect it…maybe a good place for ocean level too. A NC temp station in the Piedmont would suffice as one of 50 stations for the US. You will discover differences in nearby temp stations if the land is hilly.

Reply to  T.C. Clark
October 9, 2020 6:32 pm

Refer to the article a couple of days ago (I thought it was a post, but apparently a link to a paper in one of the comments). Small undeveloped island that has records back to 1915 – shows a statistically zero change temperature trend. The graph could have been one of those that I generated ten years ago for Tombstone, Arizona – with records back to the 1880s.

(The trend line is actually very slightly a cooling one in both series – but not significant. Off the top of my head, the Tombstone one was -0.07 Celsius over more than a century.)

Reply to  T.C. Clark
October 10, 2020 1:43 am

So reductionist I can’t keep from laughing.

Reply to  icisil
October 9, 2020 5:44 pm

It can be worse than that in North Carolina. I remember one night we traveled from Raleigh to Durham (yes they are two cities.. like Dallas and Ft Worth) for dinner in December. We left around 6pm where it was around 70F, drove through a warm front halfway there and got out of the car in an ice storm. Had a great dinner, went out and scraped the ice off, drove back through the front and got out of the car in 70F air. It was about a 30 mile drive. Coastal fronts in the Southeast US are notorious for temperature changes from one side to the other in the winter.

Reply to  rbabcock
October 9, 2020 6:08 pm

Colorado is the state for temp record changes….like 70F from one day to the next. The last time earth had some real climate change was 12000 to 15000 years ago …the Younger-Dryas Period was within this time and the average temp first warmed 20C from an ice age and then plunged back 20C and then rose 20C to give us the relatively decent climate that has been warm enough for civilization to develop.

In the Real World
Reply to  T.C. Clark
October 10, 2020 8:53 am

The Green loonies will always use one odd temp to try to claim a new record .They did it last year from a site on Heathrow airport at the time that 6 large jets had just taken off or landed .

And then they are now claiming that this September was the ” Hottest one ever ” .
CET temp records go back to 1659 and show that it was only equal 122 nd warmest .

But actual facts have never yet stopped their lies .

Reply to  T.C. Clark
October 13, 2020 1:16 pm

I believe 2 temp stations would suffice for global temp.

I call this bathtub thinking and normally it applies to sea levels but in this case applies to temperature. This kind of thinking assumes homogeneity of global temperature over time whereas we have archaeological evidence from Greenland that sustained higher temperatures can persist regionally for at least decades because parts of Greenland now in permafrost were once habitable by Vikings

October 9, 2020 4:39 pm

Cmon man – What’s a heatwave.
Each jurisdiction appears to have a different definition of heatwave.
Additionally the definition of heatwave used doesn’t necessarily have a connection to the scenario that causes the most damage.
In UK a heatwave is when the temperature goes higher than 25-28 degrees for three consecutive days. Poms love heatwaves.

Pop Piasa
October 9, 2020 5:29 pm

Not to be abrupt, but who made CA the benchmark of climate?
It in no way exemplifies the typical conditions of the rest of the continent. It is a place that has always personified the daily gamble of “whether the weather” and “Earthshaking events”.
Seems like a cherry-pick for the alarmist culture that has by some irony, moved there expecting perfect weather and a garden of Eden.

Reply to  Pop Piasa
October 9, 2020 5:44 pm

The whole alarmist theory breaks down trying quantify damages at a regional level.

Reply to  Pop Piasa
October 9, 2020 5:58 pm

Not cherry picking but almond picking.
Will higher CO2 and higher temperature ( which includes less frost days) damage or benefit California’s almond industry?
Now assess for grapes and all other crops and regions.
Some regions of USA will benefit immensely from more CO2 and higher temperature.

Pat from kerbob
Reply to  Waza
October 9, 2020 8:12 pm

And ALL regions of canada

“I want some more please”.

Reply to  Pop Piasa
October 9, 2020 10:56 pm

“but who made CA the benchmark of climate?”

Ummm.. California did….

All the ruckus about climate change causing the fires.

OOPS heat waves are decreasing !

October 9, 2020 5:34 pm

In Victoria Australia, in late January 2009 there was a heatwave.
Max temperature in Melbourne
27th 36.4 deg
28th 43.4 deg
29th 44.3 deg
30th 45.1 deg
It was estimated that this heatwave killed 374 mostly elderly people.
The total deaths for January 2009 in Victoria was 3076
The total death for July 2009 in Victoria was 3250
Long prolonged winters are more dangerous than short summer heatwaves.

BTW the BLack Saturday Bushfires were on February 7th which was 46.4 with high winds BUT not a heatwave.

October 9, 2020 6:21 pm

Bombarded by SCAM adverts !!!
Dick Smith said these adverts using his image promoting Bitcoin are a SCAM.
Any advert using a celebrity or TV show to push investment/Bitcoins is 99.99% SCAM.
“Banks Can’t Stop You Doing This and They Hate It – Don’t Miss out” are probably a SCAM.

Reply to  tygrus
October 10, 2020 12:37 am

Use ‘Adblock’ & or ‘Ghostery’ stops ALL adverts (both are free for basic);
also dump Google [ it tracks your every move ] & move to ‘Duck duck go’ (also free)
been using them for yrs… no problems, no adds, no tracking.

Shawn Marshall
Reply to  saveenergy
October 10, 2020 4:27 am


Reply to  saveenergy
October 10, 2020 8:48 am

The Brave browser has it built in. Based on Google’s Chrome engine but without Google. I use it almost exclusively on my Mac. Fast and efficient.

Tom Abbott
Reply to  saveenergy
October 10, 2020 10:14 am

I use a script blocker and it has a feature that lists all the websites that are being blocked on any particular website, and google websites are connecting to most of the websites you are visiting, so I think Google can track your website movements even if you don’t use their search engine.

You need a VPN or something like that to prevent being traced. Or software that tricks websites into thinking you are someone else.

October 9, 2020 7:25 pm

These results are consistent with aggregate California extreme temeperatures that I determined based on twenty-seven better sited weather stations with records back at least ninety years, and geographically distributed throughout the state. See the chart here (scroll down to the second graph). The percentages of both the hottest temperature days and the coldest temperature days have trended downward over the last century, more dramatically for coldest temperature days. In all of California except the southeast region of the Mohave and Sonora Deserts, the decrease in hottest temperatures has been particularly marked. Included on the graph is the change in atmospheric carbon dioxide, showing a very weak inverse relationship with the distribution of cold days, and a very weak correlation (r = 0.17) with the distribution of hot days.

October 9, 2020 7:42 pm

Averaging all of California is misleading as well. Northern California’s maximum temperatures have been cooling since 1930 while southern California has warmed. Minimum temperatures have warmed all over. These conflicting trends suggest regional dynamics are operating not Global warming.

Likewise 38% of the USA weather stations with data over at least 70 years show cooling trends. That can only be explained by local dynamics.

October 9, 2020 11:26 pm

California has had a lot of strong droughts in the past..

.. now is not one of them

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October 10, 2020 12:41 am

There is a much better way to check the claims of people like Gov Newsom that California wildfires are caused by global warming. California has 7 stations in the Climate Reference Network. These stations are from all different parts of the state. The CRN stations are high quality in terms of sighting and temperatures are measured continuously with state-of-the-art equipment.

Its easy to dump down the data and perform statistical tests for a time trend in measured temperatures. The first step is to de-seasonalize the data, Then its a trivial exercise to perform a time-trend test. Not surprising to readers here – there isn’t a CA station in the CRN network that has a statistically significant positive trend in temperature. Its not even close. Gov Newsom is just ignorant, but we knew that.

Reply to  Nelson
October 10, 2020 3:15 am

USCRN shows September 2020 as the 3rd coldest since 2006 in the USA.

And I check one of the Californian USCRN sites.. (used monthly datafile)

You are correct, basically zero trend.

Reply to  Nelson
October 10, 2020 3:29 am

Zero trend in Precipitation at that site, as well.

Reply to  Nelson
October 10, 2020 5:05 am

Well , I now have 3 of the USCRN sites in CA sorted.

There is a very tiny +ve temperature trend in 2 of them

No trend in Maximum temperatures

No trend in Minimum temperature

And so sign at all of anything at all unusual about 2020.

Where are these fairy tales of extreme high temperatures coming from ?

Is NOAA measuring temperature at a fire front or something ???

October 10, 2020 12:42 am

‘The exercise only takes us up to 2014’… a growing trend on this site, to publish studies with data only up to 2012-15, and misleading, given that the last 5 years have seen many exceptional weather conditions …

2020 – record California temperatures, for example

Reply to  griff
October 10, 2020 2:43 am

No kidding Griff, it’s weird how CO2 has been increasing and increasing and then in 2020 it becomes a record?

That crazy CO2 was just waiting to attack 😉

Reply to  griff
October 10, 2020 2:56 am

Thanks for confirming IT IS WEATHER, not climate

Well done griff. ! 🙂

The big warm blob off the coast, and a very strong El Nino had nothing to do with it , of course.. right griff.

Do you have ANY scientific evidence that this warm WEATHER was caused by human released CO2 ???

Still waiting .. and waiting !

Did you know…….

USCRN has dropped to 0.22ºC anomaly this September, making this September the 3rd coldest since 2006 according to the pristine non-urban temperature series.

Reply to  griff
October 10, 2020 3:40 am

Just checked Santa Barbara USCRN,

It has a very slight +ve trend, but the peak is in 2015. 2020 is nowhere near.

When I get time. I’ll combine the seven USCRN stations in California..

I doubt will be a big 2020 peak temperature.

Or perhaps griff could do that for us.. 😉

Reply to  fred250
October 10, 2020 8:02 am

Fred, the trend is not statistically significant. I did the analysis on all 7 stations.

Reply to  Nelson
October 10, 2020 1:00 pm

Agree completely.

As I said.. very tiny. Obviously not going to be “significant” in a statistical sense.

Hadn’t got that far yet with the analysis, was 11pm after a long day elsewhere.

Reply to  griff
October 10, 2020 5:06 am

“2020 – record California temperatures, for example”

Not at any USCRN site there isn’t !

If anything 2020 is slightly cooler.

Reply to  griff
October 10, 2020 5:32 am

Here’s Stovepipe Wells, USCRN max/min graph

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Talk about NOTHING happening !

Reply to  griff
October 10, 2020 5:03 pm

After looking at all 7 USCRN data sets.. in the last 12 year (time period when all stations were reporting)

1. There is NO evidence of any significant warming.

2. There is no significant trend in precipitation.

3. There is NO evidence of any 2020 “record temperatures”
Fallbrook was the only one of the 7 stations where 2020 had the highest temperature

4. There is NO trend in either Maximum or Minimum temperatures.

No wonder the alarmists avoid the USCRN data like it was Covid-19 !

Geoff Sherrington
October 10, 2020 12:56 am

Sonce 2013 I have written and updated some Australian capital city data on heat waves.
The officc/ial line here is that heatwaves are becoming hotter, longer and more frequent.
Historical data shows mostly that they are not, for the cities where most people live.

There is a real danger that, for example, planners of responses to future fires might be wrong because the official meme is wrong.

Search the Jo Nova blog for “Heatwaves Sherrington” for a several fuller accounts. Geoff S

Reply to  Geoff Sherrington
October 10, 2020 3:46 am

The trouble is getting the people in power to overcome their brain-washing and/or political wimpiness and actually accept what the actual real data shows.

The anti-CO2/climate change agenda really has been a quiet effective CON-JOB / SCAM.

October 10, 2020 3:03 am

For you average luvvie, a single very hot day is all the proof needed for heating alarmism.
A single storm for an increasing extremes story.
With science like this we’re just talking to ourselves.

October 10, 2020 3:49 am

The wind mills are working 😉

Shawn Marshall
October 10, 2020 4:32 am


October 10, 2020 10:40 pm

California and much of the southern parts of Australia have similar climates
The critical factor in those parts of Australia for bushfires is preceding long periods of drought which dries out the flammable native flora and the soil-with lightning strikes, runaway burning off and arsonists doing the rest., particularly if there has been accumulation of forest floor fuel
Sure prolonged heatwaves also worsen fire conditions but they tend to follow drought because when the soil is very dry incoming solar radiation heats it and vegetation up, whereas if there has been an El Nina weather event with lots of rain the incoming solar radiation loses much of its energy in evaporation rather than raising temperatures so much
I am unfamiliar with California weather patterns but understand there have been several years of drought
While I don’t know the possible causes of Californian droughts here in Australia their sources are the shifting conditions in the very large ocean weather systems originating in the Indian , Southern and Pacific oceans which surround our island continent -but local media here are quick to claim the warmer temperatures and fires are caused by AGW
Last year the devastating drought that gripped southern Australia was due to the interaction of the Indian Ocean Dipole and the Southern Annular Mode This year the La Nina cycle from the Pacific Ocean is dominant with the result being many places have already had a year’s rainfall before the start of October with floods an emerging problem

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