July average maxima in San Francisco coolest since 1971

Supposedly Mark Twain once asserted: “The coldest winter I ever spent was a summer in San Francisco.” This July was cold, and Twain’s quote? Well, read on.

San Francisco - click to enlarge - image: Wikimedia

My friend Jan Null, former lead forecaster for the NWS in California, is now runs a private forecasting and forensic weather services business. He sends out regular emails with note of interest. Here is one of them:

With an average monthly maximum  July temperature of just 63.1 degrees, San Francisco had its coolest July since 1971 and the 13th coolest in the past 97 years.  Only one day reached the 70 degree mark (72 degrees on 7/3 and no day after the 17th exceeded 64 degrees.

Downtown San Francisco, CA

Average July monthly maximum temperatures

(See table below)

Rank Year Avg. Max (°F)
1 1962 60.52
2 1951 61.13
3 1944 61.55
4 1956 61.90
5 1965 61.94
6 1914 62.06
7 1955 62.52
8 1971 62.68
9 1919 62.90
10 1949 63.00
11 1968 63.00
12 1950 63.03
13 2010 63.10
14 1970 63.13
15 1969 63.29
16 1938 63.32
17 1982 63.32
18 1960 63.39
19 1958 63.55
20 1981 63.71
21 1966 63.81
22 2000 63.84
23 1953 63.87
24 1943 63.90
25 1952 63.94
26 1967 63.94
27 1978 64.06
28 1920 64.10
29 1945 64.13
30 1976 64.23
31 1973 64.32
32 1937 64.39
33 1928 64.42
34 1939 64.42
35 1975 64.52
36 1999 64.55
37 1964 64.61
38 1942 64.68
39 1924 64.71
40 1927 64.77
41 1948 64.87
42 1980 64.87
43 1941 64.94
44 1977 64.94
45 1930 65.06

Jan Null

Certified Consulting Meteorologist

Golden Gate Weather Services

Webpage: http://ggweather.com


About the Twain quote: Snopes.com reports that he never said it.


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another nail in the coffin of the ASFW alarmists!!

Wasn’t 1971 cooler (62.68) than 1970 (63.13), which would require another caption for the entire entry?

yes a typo in the title, fixed. Thanks Anthony


I doubt any of us will still be alive the next time there is a “hottest year on record”.


Now let’s rank the values you posted by year (I would love to have the full dataset, but this is more than enough):
1914 62.06
1919 62.9
1920 64.1
1924 64.71
1927 64.77
1928 64.42
1930 65.06
1937 64.39
1938 63.32
1939 64.42
1941 64.94
1942 64.68
1943 63.9
1944 61.55
1945 64.13
1948 64.87
1949 63
1950 63.03
1951 61.13
1952 63.94
1953 63.87
1955 62.52
1956 61.9
1958 63.55
1960 63.39
1962 60.52
1964 64.61
1965 61.94
1966 63.81
1967 63.94
1968 63
1969 63.29
1970 63.13
1971 62.68
1973 64.32
1975 64.52
1976 64.23
1977 64.94
1978 64.06
1980 64.87
1981 63.71
1982 63.32
1999 64.55
2000 63.84
2010 63.1
So out of the 45 coldest years (which is probably 1/3 of the dataset) only 5 (1/9th of them) are in the last 30 years….


The Washington Post just proclaimed the hottest DC summer evah. Or maybe the 2nd hottest.

Tom Harley

Question: how much different was the temperature when the heavy smogs of the ’70s prevailed, to the cleaner, less smoggy days today?

Patrick Davis

Yet again, the alarmist MSN in Australia reports mostly events like heatwaves in Russia, forest fires in Southern California and floods in Pakistan, they don’t mention it, but you can feel it, the pro-AGW slant. But cold, is just weather, right? Well, maybe not, yesterday there was one 30 second report of an “antarctic blast” dumping quite a bit of snow in the Blue and Snowy mountain areas. Bumper snow season in Australia and New Zealand this winter.
The election is on Ausgust 21st (And as it turns out, I don’t qualify to vote! Well if I had sorted out my citizenship before Ms Gillard pushed KRudd747 aside via a sturdy knife in the back and pulled an early election, I might have. Oh well! 3 more years! 3 more years!) and if Labor form a coalition with the Greens, very probable, we can say good bye to the lucky country. All manner of “planet saving” legislation is just waiting in the wings. Incidentally, almost 1.5 million new voters registered to vote this year. Will be an interesting election.

Roger Carr

From the link to Snopes.com: It may be California, and it may be lovely, but the wind can be vicious, and those summertime temperatures can be disappointing bordering on “in danger of freezing if one doesn’t keep moving.”
The alarmists will shortly need to be moving from a canter into a gallop…

Amino Acids in Meteorites

With PDO (-) and La Nina forming it could be a cold winter in San Francisco too.

I allus told you we libruls were cool.

Jim Cole

Interesting factoid, but let’s face it.
When the 45th least-cold July in nearly 100 years only musters 65F, “Baghdad By the Bay” ain’t exactly cozy. Time to retreat to the Redwood Room at the Clift Hotel for a proper martini!
Makes me miss Herb Caen.


Anthony, trivial but Jan overlooked 1971 (#8) as “coolest July since”.
REPLY: No that’s an error on my part in copy paste, and writing the title, Fixed thanks. -A

As far as I can tell it was absurdly cold and gloomy in San Diego in July too. Fricking Brrrrr!

My read of the above table is that it’s the coolest since 1971, position 8 on the list, since 1970 was a bit warmer than 2010. When one says “coolest since…” it refers to time when it was colder. But you, Anthony, have shown a year that was a bit warmer than 2010.
REPLY: Typo in highlight, thanks for pointing it out. I shouldn’t edit when I’m tired. -A

“Sans summer Fransisco”?

I’m NOT holding my breath waiting on the MSM or the Weather Channel to report this, blue is just not my color.


you should give the unit (°F) for Avg. Max column.

in the USA, it is assumed, and if those were C, people would be screaming about a heat wave -Anthony

But — but — but — it was the 28th *warmest* July evah!
The post above is one reason I like to see the actual temperatures, rather than a graph of anomalies. When the difference between the warmest and the coolest is less than four and a half degrees, it puts some perspective back into the discussion.

Don E

I was alive 34 of those 45 years and I didn’t notice because cold and foggy is normal. I did notice the unusual warming period that ended about three years ago. For me, normal is cold and foggy between the spring and fall heat waves.

dennis ward

Nice bit of cherry picking.
REPLY: Noting records or events in context of records is not cherry picking, they are singular points. Either they exceed +/- previous records or they don’t. For example:

430 AM PDT FRI JUL 10 2010

But you can be certain that if it was the warmest July SFO maxima since 1971 it would be screamed about it headlines.
– Anthony

Bill Jamison

San Diego had it’s coolest July since 1933! It ranked 14th all-time for coolest July, which is impressive considering the changes in locations and the urban growth that downtown San Diego has experienced in the last 77 years.
There were only 8 days with a high temp of 70 or above, compared to 9 in January!
I wonder how much money this cool weather has saved people on their electric bills? While the immediate coastal areas benefitted the most, inland areas have also been running at least 10 degrees below normal too – and that’s a good thing for them.

REPLY: Typo in highlight, thanks for pointing it out. I shouldn’t edit when I’m tired. -A

Well Anthony, you are the hero who blogs in his spare time even when he is tired. I have my own blog but when I’m tired I just say: “I’ll leave it till tomorrow” and two to three weeks later it gets done!
Second, I notice that we skeptics air our dirty laundry in public — if we make a mistake it is out in the open and so is the retraction. Unlike AGW. Kudos…

UK Sceptic

It’s officially the warmest year on record isn’t it? What was that? The needle’s stuck you say? Better give the turntable a nudge to make the needle jump the right way…

Grant Hillemeyer

I work in a building on the old naval air station in Alameda. Our shop Is on the lagoon with windows facing the city. The summer fog has been very persistent, burning off back to the coast by 10:00 to 11:00, rolling back in by 4 or so (ruining all the sunsets) I was over there on top of the hills a couple of times last month, streets wet, trees dripping with water, very windy. Makes for excellent sailing in the afternoons!


I’m not cruel, but every physical value requires its unit. I’m living in Germany and the people would be there screaming about a new heat wave…in the USA 😉


Something in the Bee this last Sunday related to this;
Mild weather, summer breezes keep ozone low

No sweat. Breathe easy.
Mild temperatures in the Sacramento region this summer have meant something more than freedom from perspiration.
Cool weather has brought better air quality, and fewer respiratory problems for those who suffer when ozone levels rise.
The Sacramento Metropolitan Air Quality Management District has declared just two “Spare the Air” days this summer – days when air quality reaches unhealthy levels.
Every other year this decade, officials have declared at least five by this date, and sometimes as many as 13.
This year’s two dates, July 16 and July 17, also came much later in the year than is typical.
“We’ve had a really wonderful summer for people who are troubled by bad air,” said Christina Ragsdale, spokeswoman for the district.
The quality of the air is related to the heat, or lack of it.
Ozone forms when a soup of volatile organic compounds – a variety of gases – is cooked by high temperatures and oxygen bonds into three-atom molecules: ozone.
That’s why in July 2006, when Sacramento had a record 11 days in a row with highs above 100 degrees, it had nine “Spare the Air” days in just those 11 days.
Temperatures have reached 100 degrees or higher six times this July in Sacramento, but those days have been spread out over the month.
Another key factor has helped prevent the buildup of ozone this year.
“Even when it’s been warm, we’ve had a lot of wind,” Ragsdale said. The wind slows ozone production.

How do you like “Spare the Air” days as climate marker?
See the graphic Fewer Bad-Air Days for Sacramento. Annual total bad air days by year from 2001-2010.


I hate it when reports of the “Hottest Year In The History Of The Planet” are interrupted by reality.

Gail Combs

GM says:
August 2, 2010 at 9:54 pm
Now let’s rank the values you posted by year (I would love to have the full dataset, but this is more than enough):
…So out of the 45 coldest years (which is probably 1/3 of the dataset) only 5 (1/9th of them) are in the last 30 years….
It is a coastal city , influenced by the ocean so what is the pacific ocean doing?
SEE Graphs
graph 2
However the San Francisco temperature record seems to exhibit a heat island effect when compared to the records of less populated areas.
Yosemite Park headquarters


You should lead off with “NOAA once again shows that this year is not breaking the trend of lower global average temperatures” then give the anecdote “for example, in SF, it’s been an unusually cold July.” Go from the broad data set to the sample, so as not to appear to be cherry-picking. I mean, unless the larger data set stands in your way.

Surfer Dave

Over here in Perth, Western Australia, the month of July had average minimum daily temperatures of 5.9C as against the long term average minimum for July of 7.8C, almost 2 whole degrees less! Mean maximums were “normal” with the July just gone averaging 18.2C compared to long term average of 18.3C.
Similar for June 2010 – average min of 7.1C compared to long term average of 8.4C but average maximum was 19.0C compared to long term average of 19.3C.


Hang on just a minute, those temperatures haven’t been homogenized yet !! Im sure once they are properly processed they will be the 3rd hottest on record.

What would the real temperature be if a correction was made for the UHI?


The weather in SF is mainly a function of wind direction. When the winds blow onshore, it is cool and gloomy. When the winds blow offshore, it can get hot. San Francisco’s hottest days are generally September and October when we get the wind from the East and the downslope winds from the Sierra warm things up.
That said, I live a ways South (about 50 miles) from SF and have a coastal range of mountains between me and the coast (Santa Cruz mountains). We are generally warmer than SF and not as influenced by the coastal marine layer. Not this year. It has been cool and gloomy in the mornings with a late burnoff of marine layer of clouds/fog in the mornings. Temperatures have been below normal even here. But again, we haven’t had any strong Easterly winds to push the temperatures up either.
We will see how it goes in the fall.


Don E: that sounds like west of Scotland weather. Or do I mean climate?
Anthony: Brits read this and don’t assume anything, least of all units of measurement. Please specify your units, °F in this case. We’d like it even better if you could summon the energy to be ‘global’ about this and use °C (maybe as well rather than instead of). More work, I know. Just asking.


Gail Combs:
You can not compare SF with Electra or Yosemite or especially Independence. Those cities are in completely different climactic regions. Yosemite Park HQ is in a valley in the Sierra Nevada mountains. Electra is in “gold country” also in the Sierra foothills. Independence is on the other side of the Sierras near the Nevada border.
One would have to compare San Francisco with places like Half Moon Bay, Santa Cruz, and Bodega Bay. You will want to compare other coastal areas to make sure you get apples to apples.


Dang spellcheck, meant climatic … jeez.

I’ve been saying it was cold here…
Today I ripped out one of my tomato plants. Type name was “San Francisco Fog” and was supposed to be cold tolerant. The Siberian was making tomatoes, but not the SF Fog. Guess we are “Siberia” cold now 😉 That’s what I’ll be growing from here on out (along with the similar “Siberia” variaety). Of interest, the Roma planted next to the Siberian is also making fruit, but with only a few seeds. I think the Siberian is acting as a cold pollinator. (It’s pollen grain growth that’s limiting in the cold…)
@GM: If you had a point, a long list of numbers showing this year was cold, and about as cold as other Way Cold years, didn’t seem to say much other than: Its COLD.
Oh, and I’m sure we’ll have LOTS more cold years going forward now that the PDO is flipped back to ’70s mode’ and the sun is on vacation.
@Tom: SFO has water on three sides and frequent winds. It’s the odd day that has smog build up at all. (It generally all gets blown down the peninsula to where I live 🙁 or gets sent over to Oakland… ) So most of the time SF temps match the water temps plus solar heating minus wind speed… Smog need not apply.
@Crosspatch: We’re probably not too far apart. I’ve had it be 103 F down here and 55 F under the fog in SF. Shocking when you leave here for there and forget to take a coat. Now anytime we head to SF, we put a coat in the car. And this year I’ve had overcast until late morning, then back again at near sundown. Dank and cold.
To those folks kvetching about the use of F: It’s what we do here. To convert it to C Anthony would have to change the published data and take precision errors. F is more precise than C, so something would be lost in the conversion. How about you learn to be multi-lingual in temperatures? We are… I use C, F, K, and even R sometimes. Depends on what works best. And F works just fine. BTW, the “traditional” units were not as slap-dash has legend leads you to think.
Take the planetary circumference in feet at the equator (131479724.6). Divide by (360 x 1000).
Recognize the number?…
Mark a circle on the ground and put a stick in the ground at the perimeter aligned with a star rising at the horizon. Put another stick 15 degrees away (you can do that without advanced tools…). Time the transit of a star from the first stick to the second with a pendulum. Count 3600 beats. Lengthen or shorten until it is exactly 3600. Congratulations. You have a 1 Rod measure. You can create this length standard anywhere with 2 sticks and a bit of string…
The old units are Just Fine. And I’ll be able to recreate them anytime I want without any government body and without doing a survey of France… and getting it a bit off (the M is a bit off, but you knew that already…)


E.M.Smith says:
August 3, 2010 at 1:10 am
I’ve been saying it was cold here…
@GM: If you had a point, a long list of numbers showing this year was cold, and about as cold as other Way Cold years, didn’t seem to say much other than: Its COLD.
Oh, and I’m sure we’ll have LOTS more cold years going forward now that the PDO is flipped back to ’70s mode’ and the sun is on vacation.

The point of the post was to show that the original post was dishonest, which should be obvious to
[snip — behave politely or take it elsewhere ~ ctm]
because I have figured our a long time ago that there is nothing to gain from that as the only weapon I as a scientist have are facts and logic and it is impossible to argue with facts and logic with people who do not see any value in those. And I am not a climatologist myself but I happened to come here by chance and I was about to scream in horror when I saw that post, so obvious is the hole in the argument. I can imagine how a climatologist would feel…
Anyway, yes, that’s the current temperatures in San Francisco maybe relatively cold. And what this means is precisely that – it’s cold in San Francisco and it hasn’t been very hot in Southern California where I am either . Which is only relevant to the argument about global climate change as far as the contribution of California to the global annual temperatures goes. Which is very small.
The same is true for the US as a whole. Another recent post was showing the map of the US and the how “cold” it is in the southern parts – that the northern part of the US are hotter than usual and that the whole of Canada is much hotter than usual was left out. Not that those on their own prove that there is warming, but this blog seems to only focus on the colder than usual regions, I wonder why.
The worst thing is that these same tactics have been beaten down to death repeatedly, yet nobody seems to listen…

Scarlet Pumpernickel

That’s why Al Gore bought his apartment there by the sea, it’s safe from that terrible global warming and the 100ft sea rise

The only logical explanation is that the State of California’s efforts to reduce CO2 emissions are working! NOT.


[snip — behave politely or take it elsewhere ~ ctm]

[Snip again. Not remotely comparable, and your screed was for worse than the use of single word. If you are unable to engage in courteous discourse you do not belong here. If you do not grasp the complete context, give yourself a few months to catch up. And please, spare us links to realclimate. You’ll notice the factual points of your comment were left intact, which is something you are unlikely to find elsewhere. It is also unlikely to continue here as editing your posts to conform to blog policy (and writing responses, such as this) is far more work than the moderators would like. So, in the future, if you continue with your lack of decorum, it is likely your comments will be deleted in their entirety. ~ ctm]


“The whole of Canada” was most certainly not “hotter” than usual. Unless, as some Torontonians seem to believe, Toronto is suddenly the whole of Canada.
It’s COLD in the west. Stupidly cold. We’ve had a few days with high peak temps that are rapidly cooled in the late afternoon. We’re a month late on our usual weather patterns. We are missing summer, and this bodes ill for the winter to come.
Whatever you’re yapping about (GM) that’s getting you snipped, your accuracy certainly seems to be lacking as well. I’m not hearing anyone in BC, Alberta, Saskatchewan or Manitoba talking about “hot”, and that’s half the country.

At a latitude of 46°37’30.000″ N, Sudbury Ontario had an average max of 27.1 C, which is around 80.8 F, for July 2010. We have had a nice warm dry summer here unlike last July which was cold and wet. Our July 2009 average max was 21.5 C (70.7) which is closer to San Francisco’s temperature this July. — John M Reynolds

Sean Peake

Codetech: We in Toronto do not believe we are the whole of Canada—we are the centre of Canada!
Here we’re having an average summer, and much better than last year. A few hot days, some humidity, generally just the way I remembered them. If NOAA or GISS shows that it was abnormally high in July, I’ll know the fix is definitely in.


Are you based in Scotland?

PeterB in Indianapolis

I think that the most accurate thing that can be said from the (partial) dataset is that the average July temperature for San Francisco is in the range of 60-65 deg. F and has been in that range for a century.


Can we really believe these numbers?? I thought in order to get an accurate temp reading for any location, your supposed to 1200 miles away! I’m so confused!


eddieo 5.25am
Scotland, yes.
How did u guess?
Been wondering why global warming wasn’t noticeable here. With WUWT now I understand.


The local meteorologist for Redding was heard to remark that it is ‘very unusual’ to have a delta breeze in the forecast for 2 weeks straight. He normally gets the charts for that phenomenon out a couple of times per year.
So, the Delta Breeze coming in through SF is stuck in the ‘ON’ position.
Just like the last 3 years, where weather patterns get stuck. Same story with the recalcitrant Sun.
Yes, I do blame these stuck phenomena on the Sun.

nandheeswaran jothi

you are new here. so, i understand your consternation.
everyone here DO believe weather is not climate. you will find that out, as you read the posts here for a while.
this post does not stand on it’s own. It is part of a complaint about the MSM. MSM has been talking up “hot Moscow”, and ignoring “Cold Siberia”. and MSM did not talk about “cold South America”, where there were snow on the beaches of Northern Argentina, which generally does not see snow.
MSM has been making a big deal out of Hot NY/Wash.DC/Phila,PA etc. but ignoring cold SanFran etc. That is what this post was about.
Context , my friend, is quite important