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Heatwave Trends In Oregon

June 30, 2021

By Paul Homewood





The Pacific Northwest heatwave now seems to have broken, with Portland maxing out at 116F. This is well above the old record of 107F, set in 1965.

We know that the heatwave this week has been the direct result of extremely rare meteorological conditions, which have driven hot desert air west over the Cascades and into what is usually a much milder region. Temperatures have been simultaneously boosted by the Fohn effect, with air masses sinking as they cross the mountains.

But is there any evidence that global warming has turbo charged the heatwave?


For that, we need to check out temperature data at Forest Grove, a small town of 10,000 just 25 miles from Portland, Oregon. The weather station there is on the Pacific University Campus in relatively unurbanised conditions.




We can see from the chart below that there has been no upward trend in the highest daily temperatures set each year (chart is only up to 2019 – no data available yet for this month).




Quite clearly if climate change was having any effect on heatwaves there, we would expect to see these trends rising.

We can also look at duration of heatwaves. The chart below shows number of days 100F and over each year. These peaked in the 1990s, since when heatwave days have returned to “normal”:






In short, what Oregon has had this week has been a freak weather event, and not a product of global warming.




All data is from CLIMOD

  1. Joe Public permalink
    June 30, 2021 2:41 pm

    But the all-time Oregon record set on separate dates in 1898 at locations ~120 miles apart remains at 119 degF

    • June 30, 2021 2:55 pm

      And The Washington State high did not beat the 2 places that made the 1898 119F record
      .. only the airport thermometer equalled the 119F

    • Sean permalink
      June 30, 2021 9:18 pm

      The NWS gives the Portland Airport weather station location as 45.59578° N, 122.60917° W. Plugging these coordinates into Google Maps puts the map marker in the elbow of two large swaths of asphalt near the fire station. This creates some doubt as to whether the weather station is producing accurate temperature data unaffected by reradiated heat from the nearby pavement.

      • Duker permalink
        July 1, 2021 12:14 am

        Good catch. But it makes clear airport temp gauges are placed to catch the exact temperature for jets taking off, its an important part of the methods for estimating distance needed a for takeoff and the thrust the engines provide

      • T Walker permalink
        July 1, 2021 8:45 am

        Dukes. You are totally correct. The trouble starts when you use the output for climatological purposes.

  2. David Allan permalink
    June 30, 2021 3:53 pm

    Excellent work, Paul.
    Bet Harrabin won’t publish your findings!!

  3. ben cosin permalink
    June 30, 2021 4:22 pm

    thankyou for this kind and prompt response. I hope other readers did not have a similar problem – or if they did, they commented on ityoursBen Cos

  4. Jack Broughton permalink
    June 30, 2021 5:15 pm

    Sadly, the damage is done. The liars have now got this mis-information into the public domain and like polar bears and flooding the public are not told that these “facts” are merely a fear-campaign.

    • Gamecock permalink
      July 1, 2021 11:06 am

      Correct. The lie is half way around the world.

  5. GeorgeLet permalink
    June 30, 2021 6:10 pm

    Every summer you can find some place on the globe that is hotter than normal. These scammers run there are like Keystone Kops

    • Ben Vorlich permalink
      July 1, 2021 6:48 am

      The DMI has temperatures north of 80’N below average. In fact they’ve been below average since the average went above zero degrees C

    • JCalvertN(UK) permalink
      July 1, 2021 1:34 am

      Also visible on Bing Maps (Birdseye view) is the presence of a socking great air-conditioner only a few metres away, at the rear of the building.

  6. Philip Mulholland permalink
    June 30, 2021 7:20 pm


    Thank you for this analysis and also for correctly identifying the meteorological weather process that caused the heat wave.
    There are different kinds of Foehn Winds and this one appears likely to have been caused by Isentropic draw-down.

    I await the final professional reports with interest.

  7. John OReilly-Cicconi permalink
    June 30, 2021 7:46 pm

    Dear Paul

    do you personally believe that anything should be done by humans that will have any effect on the global warming that has been going on since the 19th century?

    I would be very grateful for a reply as I dont know another person as knowledgeable as yourself on this matter. Perhaps in the form of a positio paper for yourself & us readers.

    Yours in hope john o’reilly-cicconi ________________________________

  8. June 30, 2021 8:45 pm

    WordPress sometimes throws up similar blogposts

  9. Graeme No.3 permalink
    June 30, 2021 10:57 pm

    Great takedown, Paul.

    But could there be a residual heating effect from all those fires as the (was it) BLM ‘movement’ ran riot in Portland burning businesses with encouragement from the Democratic administration?

    We could then blame the warming on hot air emitters.

    • Duker permalink
      July 1, 2021 12:15 am

      Dont be silly on that….. thats just so absurd

      • T Walker permalink
        July 1, 2021 8:58 am

        Duker. I think Graeme is being a little ironic here.

        What his comment does highlight is the fact that BBC has more to say on hot weather than weeks of the rioting by the left in Portland last Summer causing $billions of damage.

        Also how much news coverage did they give the record cold/snow in the same area this last Winter.

        It is why is known as the Biased Broadcasting Corp.

  10. John Hultquist permalink
    July 1, 2021 12:11 am

    Temp here 100 miles east of Seattle the max T was 10° less than Tuesday. Dropping another 10 on Thursday.

    Meanwhile off the topic of this thread:
    Panama Canal and water
    When I saw this article in the WSJ and the accompanying photo my jump to conclusion (because it is hot here) was that heat causes ship to get wider and they won’t fit in the docks. Alas, it is nothing as exciting as that.
    {Might make a good rumor, though.}

    The real deal is a claim to more frequent dry years and more erratic storms. For example, ” 4 of the past 7 years ” driest since 1950.
    Near the last we learn of
    – locks were designed for more homogeneous weather,
    – recent expansion – larger ships,
    – growing water use – people & agriculture

    Panama Canal Tackles Climate-Change Puzzle: Too Little Rainwater or Too Much – WSJ

  11. Gamecock permalink
    July 1, 2021 11:20 am

    Foehn effect. New term for me. For old weather pattern.

    Occasionally, fortunately years apart, we’ll get blocked highs in the Mississippi River valley, setting up a north west wind here. Which comes over the Appalachians, getting compression heating on the lee side. We will get temps over a 100 for days in a row.

    It’s just weather. Observable, obvious weather.

  12. C Lynch permalink
    July 1, 2021 1:48 pm

    Maybe I’m naive but I would have thought that any record affected by location or man made factors such as airport tarmac, surrounding buildings etc should be discounted or at the very least qualified on that basis. But obviously not.
    I wonder if a record cold temperature had been affected by some human factor would it be accepted without question?

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