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Latest Los Angeles Heatwave Is Not Unusual

September 8, 2020

By Paul Homewood



The LA heatwave has been making news this week:



WOODLAND HILLS, Cailf—Southern California’s heatwave brought record-setting temperatures to the region when Woodland Hills—a neighborhood in Los Angeles—reached a record high 121 degrees.

The Los Angeles Police Department tweeted that the temperature reached 121 degrees at about 1:30 p.m. at the official recording site at Pierce College in the San Fernando Valley. The neighborhood looked like a ghost town and was still 100 degrees at 7:30 p.m.

High temperatures in the San Fernando Valley are not unusual during the late summer months, but the Labor Day weekend heatwave has prompted the California Independent System Operator to declare a Stage 2 Emergency.

And there was no escape for those in the San Fernando Valley.

The National Weather Service in Los Angeles said there were record daily high temperatures set or tied at Santa Barbara Airport, Camarillo,  Downtown  Los  Angeles, Los Angeles Airport and  Long Beach Airport.


The claimed record at Woodland Hills has not been confirmed yet, but it would be 6C higher than the highest September figure.

Given that no other location has even set a record for September, the Woodland figure must be highly suspect at this stage.

But what we do know is that, even at downtown Los Angeles, just about ten miles away, no such record has been set:

Temperatures peaked at 111F on Sunday, below the record of 113F set in 2010.





The weather station at downtown is in a car park, yards away from a busy dual carriageway, and in the middle of the city:




Lemon Cove is a small town, 166 miles to the north of Los Angeles, and has a high quality, long temperature record. There temperatures peaked at 107F, well below the record high for September of 112F, set in 1904.

Many years, particularly prior to 1960, saw temperatures over 107F.





As Fox News rightly point out, high temperatures in the San Fernando Valley are not unusual during the late summer months.

And there is nothing remotely unusual about this heatwave either.

  1. It doesn't add up... permalink
    September 8, 2020 12:18 pm

    Blackouts are back because of fire risk around transmission lines. If California didn’t have to import so much power it wouldn’t be a problem. Still, at least this time it’s the Sacramento area, so the legislature gets to feel the consequences of its incompetence.

    • spetzer86 permalink
      September 8, 2020 1:38 pm

      They’ve concluded the real reason is that there’s too many people in California, so they’re working on reducing that aspect first.

  2. Tony Budd permalink
    September 8, 2020 12:32 pm

    It might be a good idea to remind the West Coast people that “Cali” means “hot” and “fornia” means “oven”. I wonder why people called it that when the climate there was obviously so much cooler…

  3. Broadlands permalink
    September 8, 2020 1:30 pm

    The puzzling thing is that regardless of the temperatures or the dryness, the seasonal weather is blamed on the rise in man-made CO2. And that leads to urgent demands that we stop using carbon and rely on renewables that cannot lower the CO2 already added. That plan seems to be a crazy thing to do.

  4. A C Osborn permalink
    September 8, 2020 2:47 pm

    The headline has been made, so even if the record does not stand it will not matter.
    All you would find if you searched would be hottest ever.
    Which od course is the intention, just like the Met Office and the BBC.

  5. September 8, 2020 5:21 pm

    Having had the misfortune of living in both the LA Basin and Central Valley earlier in my life, I would like to emphasize that comparing temperatures in LA to the Central Valley is tenuous due to significant geographical differences including an intervening mountain range. That is not to belittle Paul’s comments. He’s basically right. But the Lemon Cove temps are very typical for summer in the vicinity while the LA temps are hotter than normal. The “record” clearly needs to be screened for other causes like nearby pavement, air conditioners, or maybe the exhaust from a nearby ice cream vendor’s truck to put it in context with a recent UK “record temp”.

  6. September 8, 2020 6:46 pm

    LAT’s: “Climatologist Bill Patzert [former NASA] said Sat that Sept heat waves are not new. But the extreme heat — and the duration of heat waves — is new. Over the last century, the average temperature in Los Angeles over the entire year has increased by about 5 degrees, Patzert said.

    But the average temperature for the months of August and September has increased by 8 to 9 degrees, he said.

    Although one- to two-day heat waves were the norm in the middle of the century, “now we see one-week heat waves,” he said.”

    Looked at some of the still standing record highs for L.A. 3-4 (perhaps longer) record heat waves were around way back then – prior to the 1950’s. What I don’t know is how many additional day’s record highs, associated w/ these, have got picked off over the years – the 1917 heat wave might be a good example. From NWS:

    June 1, 1879 – 100
    June 2, 1879 – 104
    June 3, 1879 – 99

    June 5, 1890 – 98
    June 6, 1890 – 102
    June 7, 1890 – 105
    June 8, 1890 – 99

    Now look at this:

    June 14, 1917 – 100
    June 15, 1981 – 102*
    June 16, 1981 – 105*
    June 17, 1917 – 105

    * I’d bet that the 2 day 1981 heat wave just beat out the middle 2 of 4 days (or more) of the 1917 heat wave.

    July 24, 1891 – 103
    July 25, 1891 – 109 – Still standing as the all-time record high for the month of July.
    July 26, 1891 – 102

    Aug 17, 1885 – 104
    Aug 18, 1885 – 102
    Aug 19, 1885 – 106 – Still standing as the all-time record high for the month of August

  7. September 8, 2020 6:56 pm

    Drats, Left off September:

    Los Angeles – Still standing record high temperatures – September

    Sept 18, 1939 – 103
    Sept 19, 1939 – 104
    Sept 20, 1939 – 107

    Of note – in that time frame . . other still standing high temp records.

    Sept 17, 1913 – 108
    Sept 21, 1885 – 108
    Sept 22, 1883 – 104

    All in all, of the 30 days in Sept, 14 high records still standing were set prior to 1970.

  8. mjr permalink
    September 8, 2020 7:03 pm

    BBC weather today has been featuring on the big temperature swing in Denver where it has dropped from “well over 90” to 32 ish,,, so a drop of 60. They have commented that Denver has had its highest ever August temperatures and the cold snap is unusually early and have said the temperature change is exceptional.
    Except it isn’t. I am not sure if this is a one day change – looks more like over a couple of days. See this chart .
    There have been 6 one day changes of 60 degrees or more … 4 being in the 19th century.. And this is just for Denver. Other parts of the USA have higher changes

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