Heat Wave Ending, & Big Change For Early August

9pm Monday

We hit 92 in Portland today, a few degrees below my 95 degree forecast high due to a little more marine air moving inland plus a thick layer of smoke overhead.

Todays Observed Highs OrWa 2017

Notice Kelso/Longview barely made it to 80 degrees!  A clear sign that someone has turned on nature’s air-conditioning west of the Cascades, but it’ll take another day for us to drop into the 80s here in the metro area.

Today was the NINTH consecutive 90 degree day in Portland, the 2nd longest streak on record.  It may have been the last 90 of this heat wave, more on that below.

90 degree streak history

We’ve set a new record for # of 90 degree days in ANY month; the new record is 15 as of today.  We’ve never seen so many 90+ days in one month here.  When you average all 30 days of the month so far, the temperature of 73.98 degrees puts July 2018 firmly in 2nd place for hottest month of all-time.  That’s just barely behind July 1985.

90 Degree July Days

Due to a thicker marine layer tomorrow (with some morning clouds), I think it’s unlikely we hit 90 again tomorrow in the metro area…likely topping out in the 85-88 degree range…much better!

We sure have a dramatic change coming Thursday and beyond.  First we get a huge marine push Wednesday night.  Models show the marine layer thickening up to around 5,000′ or so by Thursday AM.  A marine layer like that will keep us cloudy and in the low-mid 70s at the warmest point during the afternoon…quite refreshing! Expect a similar setup Friday.

By the way, July ends tomorrow and we’ll set a new record for the driest late spring & early summer on record in Portland (May-July).We’ve never seen it dry out so early in the late spring and remain dry right on through the summer, although 2015 & 1992 were close.

Mark Dry Spell Summer

Salem records go back quite a bit further in time, yet it’s still the driest down there as well with only 1922 and 1924 close.  Hopefully we’ll get a “September miracle” downpour again this year like the one that doused the Eagle Creek Fire last year.

This coming weekend will likely be dry, but once we move into later Sunday and the rest of next week the forecast gets tricky; rain showers have become a real possibility.  That’s because models are showing a sharp upper-level trough with cooler air and showers moving down to its typical “June position” just offshore.  You see the ECMWF forecast from both Tuesday and the end of next week here:


In this situation details are all over the place with each run of each model showing different disturbances rotating out of the trough and over the Pacific Northwest.  To see the possibilities you can look at the ECMWF ensembles:


Each horizontal line on the upper half of the chart is one of the “ensemble members”.  Time goes from now on the left to 15 days from now on the right.  Notice there’s some decent agreement on showers AT SOME POINT between August 5th and 10th (next work-week).  Seems to be quite a bit of clustering around the 6th-8th too.  Hmmm.  We could end up with more than just a sprinkle…could actually be a quarter-inch of rain or more.  It’s still quite far out, so to summarize:


Of course you can probably guess that we can forget about 90s during that time.  Check out the ECMWF ensembles for temperature…below average for most of the time from this Thursday through the following 7 days.


Does this mean all of August will be cloudy, cool, & showery?  Absolutely not, but it’s very clear the first 10 days of the month will be far different than July!

Chief Meteorologist Mark Nelsen

45 Responses to Heat Wave Ending, & Big Change For Early August

  1. Jason Pyktel says:

    Get a updated article please. we are currently looking at 90 degrees weather in august and the rain disappeared.

  2. Ken in Wood Village says:

    Hmmm, interesting radar. I can see thunderstorms off to my NE. They kind of look like the could be drifting SW. 🤔😏

  3. Paul D says:

    If Tuesday through Friday hit 90+, that makes 24 90+ days for the year. Only 6 more after that to break the record. I’d be surprised if it doesn’t happen.

  4. K says:

    Things keep trending hotter and hotter…

    • Paul D says:

      Not the least bit surprised. August has to beat July when it comes to heat.

      This blog was a late April Fools joke, right?

      • K says:

        I don’t like the way this Fire season is going. The cooler and wetter, the better. I’m returning to Portland from abroad in about a week, so I hope cooler temperatures grace the rest of August (though I doubt it the way trends are going).

  5. .04″ in the gauge this morning. First measurable precip in over a month.

  6. alohabb says:

    Sitting in 77 depoint and 85 degrees right now with rain and thunder. Interesting feeling.

  7. Roland Derksen says:

    We were supposed to get showers today, but that’s not going to happen now, as skies have cleared up over the afternoon. Curious to see that July 1985 was Portland’s officially warmest July: That was a warm one for us too, but not anywhere close to this past July 2018. Instead it was best known for being very dry here-just a trace of precipitation.

  8. Tyler Mode in Battle Ground says:

    Looks like Barrow will likely end it’s longest streak of above freezing temps for the year above freezing at 22 days. 32 yesterday morning with some snow, and freezing again this morning.

    • W7ENK says:

      And thus begins Winter’s slow march down from the North. How far South with the old man come this time, and how much of the goods will he be bringing down with him for us?

      FWIW, this Winter falls into Portland’s (fairly well) established 5-year cycle of big snow years…

  9. Joshua Lake Oswego says:

    It’s now looking like it will be 90 plus all next week. This is getting silly. So much for the big change in early August. Mark, you are the man and the best in the biz, but you are going to eat your words “forget about 90s” in reference to next week’s weather.

    • Paul D says:

      What happened?!? Just when we thought we were getting some relief it’s back to the 90’s!

      This sucks!

    • W7ENK says:

      Okay guys, rather than whining about something that hasn’t happened yet, why not get outside and enjoy the next 2 days of 75 degree clouds and drizzle?

      Sheesh, y’all complaining right in the middle of everything you’ve been crying for… never happy. Come on.

  10. W7ENK says:

    Just ended July with 0.00″ of rainfall. Had only a Trace amount on 7/4 and again on 7/5, but those don’t count as accumulation.

    I highly doubt we’ll make it two consecutive months.

  11. Lee Wilson says:

    Oh and on a Side note:
    We have trees dropping leaves early and some have begun to change colors.

    I think We may be in for an early fall.

    I wouldn’t mind an early fall .

    Can’t wait to use our system to run inflatables and Christmas lights 🙂

    • Joshua Lake Oswego says:

      The trees are dropping leaves and changing color because they are in survival mode. It’s not a sign of an early fall. They are extremely stressed. Driving around, there are so many dead trees everywhere. If we keep having these crazy long and hot summers, our landscape will look a lot different.

      On a side note… are we going to pretend we haven’t seen the last couple of model runs? Bye bye any chance of rain and cool weather. The Euro has us up to 100 next week and a few days in the 90s. I’m not surprised, but I am extremely disappointed. The ensembles aren’t as bad as the operational, but aside from a very brief two day cooldown, every day in the forseable future is above average or average at best. You might need to delete your blog post, Mark.

    • W7ENK says:

      Exactly, I was about to say the same thing.

      Maples, especially ornamental/landscape varieties like Red Maple, Sunset Maple and Sugar Maple are particularly susceptible to Summertime stress. The heat and the lack of water freaks them out. They’ll change color in July, and some even start dropping their leaves by early August. It’s not a sign of an early Fall, it’s a sign that the trees are unhealthy and close to dying.

      My neighbors across the street lost one in 2015, the dry Summer was too much for it and it didn’t grow any new foliage the next Spring.

  12. Lee Wilson says:

    Called up the PUD, and they said we are doing very well and were amount the top 5 for the lowest power bill.
    We were at a whole whopping $56.oo.

    Others had bills at 200 or higher.

    • Paul D says:

      I wonder how low some people keep their thermostats. My electricity bills are under $100 (closer to $80 most the time) and I cool a 2600+ sq ft house. I keep mine at 74 during the day, and then drop the temperature a degree every couple hours while I sleep and end up at 70 by morning.

  13. 85˚F yesterday. Felt hotter because I had been away for a week so my home hadn’t been aired out at night at all. Took quite a few hours for it to cool down yesterday night. I ended up sleeping on the living room couch because it was too warm in my upstairs bedroom.

    77˚F today. The cooldown is already underway for me. I will not complain if there is a showery spell with highs in the 60’s (as forecast). I’ve been enjoying the sun but everything is bone-dry; the trees need some water!

  14. Paul D says:

    Looks like PDX isn’t going to hit 90 today. One day short of tying the 10 day consecutive 90+ record. Oh well, better luck NEVER! 🙂

  15. WEATHERDAN says:

    81 on our way to 91. Last 90 degree day until the 10th. Then it looks another heat wave. This far South of the low we (Salem) might not see any showers. Still the next 10 days will be cooler. Probably 77-85. A nice refreshing change of pace before the heat cranks back up. Peace.

  16. Roland Derksen says:

    Yesterday my maximum was 92.8F- exactly 0.2F below the hottest day for 2018, which came on June 18th. So close! But, looking ahead, I’m happy it’s getting cooler for a while. it doesn’t occurr often, but we sometimes get a showery, unsettled period in early August up here, though it happens more times late in the month.

    • In 2015, I think I got about 3″ of rain total in August. There was a five-thunderstorm day on the 14th (first four were chintzy, but the final one was epic). Then there was the exceptional early-season wind/rain event later in the month that gave the whole region a widespread drenching. And that was in a much warmer-than-average summer overall!

      • Roland Derksen says:

        About the same story for that month here as well, Rubus, except for the thunderstorm on the 14th. (nothing here). I want a couple of rainy days this month, but nothing too heavy. Remember the last day of August 2010?

  17. Jason Hougak says:

    We had our hot/ dry now it’s time for cold/ rain/ thunderstorms/ hail/… real weather action!

    • W7ENK says:

      In all reality, you’re about a month early there, man…

      A bit of rain to settle the dust/smoke and moisten up the ground/forest would be a welcome reprieve, but lets not jump in full-time until it’s due.

    • pappoose in scappoose says:

      A “June position” trough would be a good start. Bring it!

  18. Larry says:

    Ready for some rain, if nothing else to wash some of this smoke out of the air. Looks like Los Angeles out there.

  19. W7ENK says:

    Yay, free sky water!!

    … maybe. ( ͡° ͜ʖ ͡°)

  20. Say it with me everyone: AAAAAaaaaahhhhhh!!!!!

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