Heat Wave: Confidence Growing We Will See Hottest Temps On Record In Portland

9pm Thursday…

This is just a brief post because NOTHING has changed meteorologically with the weekend forecast. All the points from yesterday are still valid. Just a tweak here/there


  • What will likely be the hottest heatwave on record in the Portland area (and much of northern OR/southern WA) arrives tomorrow and continues through Monday. And there’s a good chance we remain at/above 90 the rest of next work week.
  • Expect three 100+ days in Portland, and they may all be 105+
  • I’m very confident we’ll hit 106-108, and think 110 is quite possible for the first time here. Records go back to the late 1800s both at the airport and Downtown.
  • Humidity will be mostly reasonable…it sure won’t be “Bourbon Street Humid”, more like our typical heatwave humidity.
  • Overnight lows will likely end up warmest on record in Portland too. Low-mid 70s Sunday and Monday mornings. That means homes/apartments will remain dangerously warm with no chance to cool off. Typically we see reasonable overnight temps in our area.
  • The only place to cool off will be the coastline…more like 75-90 out there over the weekend. Most likely you won’t be alone if you want to play on the beaches. There’s a chance the far north coast makes it to 90 on Sunday…we’ll see.
  • I do not expect any sort of strong wind anywhere in the Northwest. BUT, some easterly wind will be felt over the metro area Sunday. Gusts 20-30 mph are possible. Enough to move an accidental fire along, but not enough to drop powerlines into trees.

I didn’t change any numbers for the weekend in today’s 7 Day Forecast, although we “overachieved” today with highs right around 90 in the metro area. I was thinking more like 86-87.

That boosts confidence in our extreme forecast numbers. Today’s forecast

850mb temperature forecasts remain the same (temp around 4,000′ overhead in Celsius). In fact, while making the forecast, I noticed both GFS & ECMWF ensemble averages matched through Sunday! +19 tomorrow, +25 Saturday, +29 Sunday (new record), +25-27 Monday PM. The only disagreement is over how quickly the upper-level low to our southwest Monday slides north offshore. Quicker movement Monday would lead to an earlier marine push = cooler high temps. Slower movement gives us another extreme day Monday. The most recent ECMWF ensemble average temps for Portland (near sea level) are just amazing. We were a few degrees warmer than forecast today. As I mentioned last night, we see that with Euro surface forecast temps in the warm season. That’s why we’re going 96 for tomorrow. Since the numbers turn so extreme Saturday-Monday, I’ve stuck with these numbers instead of going higher. I couldn’t imagine forecasting 111-114 for Portland…so I didn’t.

Check out the fresh 00z IBM Graf model, which handles warm season temperatures well. 108 Saturday, then around 114-115 Sunday! Just like the other models.

I’ve haven’t noticed this model “over-forecasting” heat in the last two warm seasons. Part of the reason we’re seeing such extreme temps (other than sun, offshore flow, and hot airmass overhead) appears to be the surfacing of that very dry subsiding air below the upper ridge. Notice the dewpoint drop both weekend afternoons. Sunday that would be relative humidity in the teens. The icing on the cake is the easterly wind Sunday. The GRAF is forecasting east wind to surface throughout the metro area that day (but not so much Saturday). It’ll be a “dry” 110 degree heat as they say…

In case you are wondering, the coastline WILL be cooler through this event. This applies to the northern Oregon and southern Washington coast…take off 5-8 degrees for Lincoln City and Newport

A few more numbers for you this evening. Portland’s all-time warm low temps. These are from the airport. With such a hot airmass, plus a larger metro area, plus a warming climate, it’s fair to assume we’ll be warmer than this.

This is dangerous for medically fragile or elderly folks…if you know any, please check in on them regularly!

That’s it for now, I’ll be on-air and online through NEXT Friday, the 2nd. I was already scheduled to work this weekend which is convenient. Make sure you are following me on Facebook: @marknelsenweather and Twitter: @marknelsenKPTV. I will be updating those much more frequently than this blog. 

Chief Meteorologist Mark Nelsen

74 Responses to Heat Wave: Confidence Growing We Will See Hottest Temps On Record In Portland

  1. Hank says:

    Forecast for Saturday and Sunday from all models I can get and all websites I know, your welcome for numbers 😉
    Weather.com 107 116
    Weather.gov 102 109 weather.gov always undershoots atleast 3 degrees so this gives me confidence in record highs.
    Myforecast.co 102 110
    Accuweather.com 106 115
    Weatherbug.com 105 115
    Timeanddate.com 103 110
    Weatherstreet.com 104 113
    Weather-forecast.com 103 114
    Weatheravenue.com 103 113
    Weatherwx.com 103 113
    Theweathernetwork.com 101 109
    00z ecmwf 106 115
    00z gfs 103 113
    00z Access-g 103 111
    00z icon 110 116
    00z norway 106 115
    00z Serbia-mos 105 115.
    Salem alltime record high is 108, June record high is 105.
    My forecast 106 114 105, seems like this is the new normal for me, giving salems temperatures after 12z 18z and 00z, I can’t do 6z since that’s in the middle of the night, stay cool out there folks 😎.

  2. Mr T (Stayton Oregon) says:

    https://www.youtube.com/watch?v=i88q0bUaMQY&t=1s How to survive extreme environments in BOTW:

  3. Mr T (Stayton Oregon) says:

    These temps are equal to the fictional Gerudo Desert in Zelda BOTW which requires either a mid level heat resistance elixir minimum or level 2 armor to survive. Some areas require level 3 armor. 🙂

  4. Tanis Leach says:

    Just finished another video. An update on the Mother of all Heatwaves (M.O.A.H) and showing how rare this truly is (without showing the datasets). Felt better than the last 2 days but still feel I need to cut some time off. Any tips are appreciated.

    • Anonymous says:

      Awesome job! I think you explain things in ways that even non-weather geeks would understand perfectly

  5. runrain says:

    Storms are given names, so why not heatwaves? We’ll need a unique name for this piece of history, so how about it all? I throw out a couple:

    “Twisted Blister”
    “Cascade Bake Off”

  6. 5OClockCharlie says:

    Don’t first degree skin burns occur at 118F? Either way, the Monday forecast is frightening.

    The worst part of all this is we go back to 90+ degree temperatures for at least the next 7 days. Oof

  7. Roman D says:

    Where are the semi pros like Rob wrath and Paul Eugene would love to see what those guys think. The new 7day is epic

  8. Roland Derksen says:

    One trend I’ve noticed in the last few years is that we get our highest temperatures of the year in June: It’s happened at my place in BC, for 3 of the last 4 years. So if it’s of any comfort to someone, we could be seeing the hottest weather of the year in the next 3 days.

    • Jake in Sandy says:

      I think a lot of locations have their warmest temps around the end of June. More typical in the southwest but it’s the longest days of the year so typically more time for warming during the day/highest sun angle.

  9. W7ENK says:

    Absurd is the word…

  10. Hank says:

    Forecast for Saturday Sunday in salem Keizer metro from all websites I know and all models I can get
    Weather.com 107 116
    Weather.gov 102 108, Weather.gov always undershoots.
    Myforecast.co 102 110
    Accuweather 106 115
    Weatherbug.com 106 114
    Timeanddate.com 102 111
    Weatherforyou.com 103 115
    Weatherstreet.com 103 113
    Weather-forecast.com 103 113
    Weatheravenue.com 109 118
    Weatherwx.com 103 116
    Theweathernetwork.com 101 110
    18z Ecmwf 106 116
    18z gfs 106 113
    18z Access-g 102 112
    18z icon 110 115
    18z Norway 106 115
    18z Serbia-mos 103 110
    My forecast, 96 today, 106 tomorrow, 114 Sunday
    Stay cool out there folks

  11. Roman D says:

    If we are gonna go big and break all records I wanna go all the way. 115f-120f and lows in the 80s let’s do this! Would love to see a week straight of this that would be incredible and then finish it off with a massive thunderstorm front from the south. Stay safe all.

  12. Joshua Lake Oswego says:

    The NAM finally jumped ship on the 18z run and now joins all other models in delaying the onshore push until the evening on Monday for the PDX metro area. If that holds true, it will be the warmest day and exceed Sunday by a few degrees. 114-118 is looking like the sweet spot.

  13. runrain says:

    Clackamas County Sheriff put out a tweet that we “could hit 100° this weekend”. I requested they correct.

    • Joshua Lake Oswego says:

      Understatement of the year.

      • Hank says:

        I’ve never heard more of an understatement, it will be at LEAST 106, but saying “could hit 100” thats so misleading its dangerous.

  14. Evan -- Cedar Mill says:

    Dew points are not very comfortable either. Nearing 60F.

  15. Evan -- Cedar Mill says:

    Brush fire in gorge. I-84 shut down.

  16. Evan -- Cedar Mill says:

    Check out Kelly Bayern’s new tweet. If onshore flow doesn’t arrive Monday, we could break the record we set on Sunday. 33C 850mb temps!! Insane!

    • Joshua Lake Oswego says:

      That’s what I have been saying, my man. Monday could legit get close to 120 and then drop 40 or more degrees within 6 hours or so. Seattle could even get above 110 on Monday.

      • Grizzly Bear says:

        120 degrees ??? Boy they must have some “good grass” in PDX !!!
        Ain’t goin’ to happen.

        • Joshua Lake Oswego says:

          I said close to 120. Do you think 117 is possible? I think at least 115 is likely. Climatology is meaningless since this is unprecedented.

        • Zach says:

          I think the all time record will certainly fall. However, I do think the GFS has constantly been too warm relative to the other models.

  17. tim says:

    Does everyone still think we could have a cool summer? if you do than your not in touch with reallity.

    • Zach says:

      Not cool, but I think there is a solid chance it goes closer to “Average” mid July-August. As I recall wasn’t 2015 kind of front heavy with the worst heat at the beginning?

      • Anonymous says:

        2015 was a more front loaded summer heat wise. There were 9 90+ days in June, 12 (7 before the 15th) July and 5 in August. So 16/26 90+ days happened before the middle of July. Fingers crossed this year follows a similar pattern and we have a “cooler” second half of summer.

    • Joshua Lake Oswego says:

      Heck, we can’t even have a cool day. Or normal day.

    • Mr T (Stayton Oregon) says:

      ‘Snow Wizard’ keeps being impressed with these ‘cool’ anomalies in the other weather forum every so often that only seems to exist in his mind. And the other person loves to blast out every warm anomaly.

    • Mr T (Stayton Oregon) says:

      I posted in the wrong reply: ‘Snow Wizard’ keeps being impressed with these ‘cool’ anomalies in the other weather forum every so often that only seems to exist in his mind. And the other person loves to blast out every warm anomaly.

      In a way I feel bad for him.

  18. Evan -- Cedar Mill says:

    Is daytime heating being stunted by a slight onshore flow at the moment?

  19. Evan -- Cedar Mill says:

    It’s crazy how just the smallest amount of onshore flow could COMPLETELY bust this forecast.

  20. ocpaul says:

    Five billion years of climate change, and all I got was this lousy heat wave.

  21. Evan -- Cedar Mill says:

    Tri cities may not get out of triple digits for 2 weeks. Shocking.

  22. Joshua Lake Oswego says:

  23. runrain says:

    We’re 12° ahead of yesterday at 10am. That would put us at 101° for a high today.

  24. Hank says:

    Every forecast i can find/get and what they show on Monday for salem Keizer metro! Your welcome for the numbers 😉
    Weather.com 115
    Weather.gov 109
    Myforecast.co 110
    Accuweather 115
    Weatherbug.com 114
    Timeanddate.com 111
    Weatherforyou.com 109
    Weatherstreet.com 111
    Weather-forecast.com 115
    Weatheravenue.com 114
    Weatherwx.com 114
    Theweathernetwork.com 109
    12z ecmwf 115
    12z gfs 115
    12z gem 105, disgustingly wrong!
    12z Access-g 111
    12z icon 117 thats what I like to see.
    12z Norway 115
    12z Serbia-mos 116
    My forecast 96 Friday 106 Saturday 114 Sunday 103 Monday, i nailed it perfectly Sunday Monday Tuesday Wednesday Thursday, but I might not get these right. Stay cool out there folks 😎.

  25. Zach says:

    Have you guys seen the WRF for tomorrow? Correct me if I am wrong, but it appears to be almost 8-10F cooler for tomorrows high than what the GFS has been showing the past few days.

    Could this imply a massive error margin for the GFS? As my understanding is the WRF is one of if not the best mesoscale for the PNW.

    • Joshua Lake Oswego says:

      It’s not even past hour 24 yet from what I can see. I will check it out when it gets to hour 36.

      The HRRR and NAM 3km support temps of 103-106 tomorrow. I think 105-107 is most likely.

    • Joshua Lake Oswego says:

      Looks like 100-104 to me on the 12z WRF-GFS for tomorrow.

      • Hank says:

        Uhm i replied twice my mistake, the first time I replied, it wasn’t loading so I replied again, now I have 2 of the same replies……

  26. Joshua Lake Oswego says:

    The 12z GFS gives PDX an 80 degree low temp Monday morning ballooning to 117 by 2pm. Cooler air arrives in the evening. Salem and south have a downright cool evening. PDX stays warm. Mark will almost certainly be bumping his Monday forecast up for the metro area. Seattle will obliterate their all-time high.

  27. sebastian says:

    114 would be a sad day for the earth!!

  28. Joshua Lake Oswego says:

    We better hope the trend of models delaying the onshore flow doesn’t continue for Monday. If it keeps up, Monday could potentially blow Sunday out of the water. The good news is that the cooler air will arrive at some point on Monday most likely and when it does, we could drop 40-50 degrees in a matter of 6 or so hours.

    • Joshua Lake Oswego says:

      The 12z NAM brings the cooler air in Monday morning. The GEM and ICON delay it until after the hottest part of the day. Things are definitely trending towards Monday being the big day for the Portland metro area and north.

      If so, at PDX, I’m going with…

      Saturday: 106
      Sunday: 113
      Monday: 116

      • Jake says:

        I agree with your dismal assessment. We’re in a lot of trouble. Our all time record of 107 being shattered, is in the bag.

        Now it is a question of how many daily, nightly and June records, we break. It will be many. Not seeing this heatwave leaving for well over a week.

        Anything above 90 is a heatwave to me as a local. I’m not enjoying this data as a weather enthusiast. Trees by 4th of July will start to suffer if we stay in the 90’s till the holiday. And I am seeing that now.

  29. tim says:

    Weatherunder ground should be illegal it’s too extreme with it’s temp forcast.

    • Jake says:

      I absolutely love WG for that reason.

      It always throws the extreme case that COULD happen. Very useful if one is planning to camp, work outside or is an extreme weather enthusiast, such as myself. It is my notification to jump on here and start sniffing around on what’s going on.

      That said, I do agree it blows the whistle too soon and I’ve written to IBM to update the algorithms already and code in some machine learning.

      Blatantly apparent it doesn’t have that tech. and misses things like the gorge factor, our costal range affecting onshore / offshore flow and how the Columbia basin in general manipulates the arctic air coming over the Rockies (everything always does a piss poor job on predicting its pace, will it make it over or not and where).

      Having said all this. It is saying 107 for Sat., 112 for Sun., and 113 for Mon.; I for one wish it was an extreme I didn’t have to see on my smartphone, ever, for PDX. I will embrace this situation with many popsicles and choice words.

  30. tim says:

    Hmm the 00z gfs is following the cooler icon model and yet i was told the icon is less accurate then gfs, apparently not.

  31. tim says:

    Again seattle will not tie or break the 103 record this is a oregon heatwave event so enjoy.

  32. Cooper Mtn. Phil says:

    110 would be awful but in the same very interested what 110 feels like! Mark, that would be absolutely ludicrous to hit 114!! Say goodbye to the tomato plants.

  33. Hank says:

    Current temperatures forecasted for Sunday in salem Keizer metro, from all models I can get and all websites I know
    Weather.com 115
    Weather.gov 109
    Myforecast.co 111
    Accuweather.com 115
    Weatherbug.com 112
    Timeanddate.com 111
    Weatherforyou.com 109
    Weatherstreet.com 111
    Weather-forecast.com 113
    Worldweatheronline.com 113
    Weatheravenue.com 117 crazyyyyy
    Weatherwx.com 113
    Theweathernetwork.com 109
    00z ecmwf 114
    00z gfs 114
    00z Access-g 112
    00z icon 115
    00z norway 115
    00z gfs-mos 115
    00z nam 106… undershooting
    My forecast, 96 106 114 102
    I’m really hoping for 118 so I can feel it on my skin, and say I experienced that, but probably won’t happen

  34. Joshua Lake Oswego says:

    Thanks, Mark. Maybe we will break Sacramento’s all-time high of 115 since we are the new Sacramento. We might even break Las Vegas’ record. Monday has biiig potential even if Sunday ‘’only’’ tops out at 110.

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