The Great 2021 Heat Wave: Saturday Updates

June 26, 2021

I’ve changed the format for today and Sunday…come back to this same link  regularly throughout each day for quick updates as we go through the rest of Saturday.  Newest information FIRST. Remember you can follow me on Twitter: @marknelsenKPTV and Facebook @marknelsenweather

9pm – Final Saturday Evening Update

What a historic day! Portland (and probably Troutdale) broke all-time temperature records…reaching 108 and 109. The final numbers…

And for the region

What’s ahead? In general the forecast hasn’t changed at all. Two more scorching hot days (hotter than today), then a strong marine push Monday evening brings in 70 degree air by 8-10pm west of the Cascades…it’s going to feel glorious. But, of course we have more record-breaking heat first. Tomorrow will be the hottest day south of Portland, due to that marine air arriving Monday midday down there. I expect at least 5 degrees warming from Salem to Eugene tomorrow, setting some all-time records. And at the coastline there will likely be a period from Noon-3pm on the north coast when temperatures soar. Tomorrow will feature conditions I never thought I’d see west of the Cascades. Temperatures to 110 and higher, a dry easterly wind, and nary a cloud in the sky. And keep in mind we’re starting much warmer tomorrow! It’ll take most of the night to get down below 80 in the urban/suburban areas

This will probably break Portland’s all-time warm low temperature. These are bit trickier to do because the weather data is collected for the calendar day (midnight to midnight). If we have a hot spell that ends with a strong marine push in the evening (that will happen Monday)? The late day temperature (close to midnight) could end up being cooler than the warm morning low. I’ve seen it happen in the past. But tomorrow night will be even warmer than tonight so I’m confident we will set this record.

For tomorrow, all models continue to agree that we’ll jump another 3-6 degrees, so I’ve put our forecast high at 112. The new 00z WRF-GFS shows a classic thermal trough from about Medford to Astoria in the afternoon

Easterly wind, although not strong, should be more widespread, and it’ll be windy in the western Gorge tomorrow. I’ve been watering my plants/lawn furiously the past two days in anticipation of that.

Look at those 104 degree highs just about touching the northern coastline beaches…plus 112 or so in the northern Willamette Valley

Then assuming cooling southwest wind doesn’t arrive until 4pm or so Monday, maybe a notch or two warmer. The east and southeasterly flow is very strong through midday Monday overhead and 850mb temps are 31-32 over PDX!

That’s it for now…I’ll be on TV at 10pm with lots more numbers.


Portland officially hit 108 today, hottest on record. More coming up by 9pm or so…dinnertime


It happened! PDX is reporting 107 degrees as the current temperature AND the high so far today. That ties the all-time 107 degree record from 1981 and 1965. I’d say about 1/2 of the time when the high is also the current temp at PDX on a sunny summer day…we end up a degree warmer. Unless the NWS puts out a special statement (seems likely), we’ll know for sure around 7:20pm. It’s quite possible today will go down as the hottest day in Portland’s history. Remember the downtown station has not gone above 107 either and those records go back into the late 1800s.

It’s possibly the 109 at Troutdale is an all-time record, looks like Vancouver is one degree short. A few thoughts

  1. Models nailed this, even better than we did. Even our “high” forecast of 106 has been exceeded. Models have been going more like 107-108 today. Sure enough, we’re doing a little better than Euro showed…which is disturbing for tomorrow.
  2. All models are forecasting between 3 and 6 degrees warming tomorrow as more of a widespread dry/hot easterly wind surfaces. That’s just unreal. Do the math and it’s obvious 110 is probably too low. Working on that now
  3. This has been an exceptional triumph of meteorological modeling. Models forecast all-time records being broken 5-7 days ahead of time.
  4. Power outages are beginning to pop up. About 3,500 PGE customers out


100 at PDX this hour, running 11 degrees above yesterday at 3pm. That puts us on track to hit our 106 degree forecast. Dewpoint is 67…very humid…yuck. Easterly (dry) wind beginning to surface in a few spots. Sure, it’s drier, but hotter. Troutdale and Scappoose jumped to 105 at 3pm! 102 at Rhododendron just below Government Camp is amazing for 1,600′ elevation. Heading toward max temps in the next 3 hours. Once drier air punches down into PDX, expect a temperature spike. Possibly the 107-108 models were forecasting was right. TODAY could be the day we set our all-time record. The drama…

Working on forecast right now and there’s a problem on the north coastline. WRF-GFS pushes easterly flow all the way to beaches and slightly beyond from about Tillamook north tomorrow. 100+ temps may be a possibility just inland from the surf from Long Beach down to Pacific City tomorrow. Maybe Astoria WILL break the all time record you see in the previous post. More later…


Looks like all is proceeding according to plan and no changes to forecast.  Rode my bike around 10-11 a.m.  Tolerable, but turning hot! 

Portland is 91 at noon; that’s plus 10 from yesterday at the same time.

Does that mean we’ll be 105?  Could be, but humidity is still high, dewpoint of 64…yuck.  That tells me the hot atmosphere overhead hasn’t surfaced or “mixed out” yet.  At some point within the next five hours, some drier air from above should surface.  When that happens the temperature will spike, then relative humidity falls.  Notice Yacolt is already 95???  It won’t matter by that time since we’ll be above 100 degrees.  Some other temps around the region are about what I would expect.  

Portland only dropped to 70 last night!  A record for the day, 2nd warmest ever in June.  The other two warmest were during the 2015 heatwave.  Of course that means you just endured the warmest night in 6 years.  Even out here at home in a rural area I only had a low of 63…rare.

Right now pressure gradients around the region are light northerly, or very light easterly across the Cascades.  Wind is light east in the Gorge, but stronger easterlies are arriving on many ridges.  I see Middle Mountain in the Hood River Valley is blowing along with Larch Mtn. and Three Corner Rock Washington.  That’s a sign the blistering hot easterly flow has begun overhead. I haven’t made the forecast yet, waiting to see what happens this afternoon with regard to raising tomorrow’s all-time high temp forecast. Morning GRAF & ECMWF models are the same…forecasting well above 110 both tomorrow and Monday as that dry east wind surfaces both days

That’s it for now.