A Warm July Ends With A Heatwave

9:00pm Monday…

It’s vacation season in the Pacific Northwest; the best weather of the year! So I’ll be joining many of you travelling across the region the next week and a half. Heading out for camping in parts of southern Oregon. No posts during that time, unless something really serious pops up (major fire close to us, huge earthquake, volcanic eruption, tsunami, etc…). I’ll be back at work Sunday August 8th.

The end of July is quickly approaching and it’s been a warm month! No record-breaking heat, or heatwaves, but consistently warmer than normal. It appears we’ll end up with at least the 5th warmest July on record, likely #3 or #4.

The western 1/3 of the USA has been sizzling so far this month, following the warmest June on record for some.

We’ve been “lucky” west of the Cascades, picking up just enough cooling onshore flow to keep us near/below 90 degrees most of the month. Portland has seen (12) 90 degree days so far this year

Yet, just slightly farther removed from that ocean air, both Salem and Eugene have seen over 20 days at/above 90!

Looking ahead, we have a heat wave on the way Wednesday-Saturday. This is what we’re thinking this evening for Portland:

No record highs, since they are generally 100+ this time of year. But four 90+ days to wrap up July.

Why is it turning hot again?

Strong high pressure bringing heat over the Rockies is far enough east to keep our temps reasonable again tomorrow. That “594” contour centered over Colorado is the center of the upper-high.

But you see it snuggles up a bit closer to us Friday and Saturday. Here’s midday Saturday; the ridge of high pressure has amplified, and southerly flow is in charge across the West Coast. This MAY bring thunderstorms north into the Cascades and Eastern Oregon. There are even a few GFS and ECMWF ensemble members sending a disturbance north with showers/thunderstorms WEST of the Cascades this weekend. But not enough to put it in the forecast. Just be aware that this weekend is not “guaranteed” dry. Keep an eye on the forecast.

This pattern doesn’t produce a hot easterly wind over the Portland area (ridge is too far east), which should keep us below 100 degrees…but just barely! Then Sunday and beyond the ridge weakens; we’re back to reasonably warm temperatures for the first few days of August. This is Tuesday (August 3rd)

By the way, we are at day #41 without rain in Portland. The last MEASURABLE rain was June 15th. There WAS a trace at PDX on July 1st. Assuming we don’t get rain in the next 12 days (possible), we’ll be up in the “top 5” range for dry spells. But for now we’re a long way from that 71 dry day record

A few more notes:

  1. I don’t expect high humidity during the upcoming heat wave, UNLESS we get some showers or thundershowers Saturday/Sunday.
  2. Overnight temperatures will be turning very warm, mid-upper 60s. This isn’t as extreme as the historic heatwave back in June, but it’s still worth checking in on elderly friends/relatives.
  3. Southerly flow = overhead fire smoke from California fires. Expect increasing haze and yellow/orange sun after Wednesday. Low-level smoke is UNLIKELY west of the Cascades since wind will be coming from the northwest and west.

Stay safe during summer vacation travels!

Chief Meteorologist Mark Nelsen

217 Responses to A Warm July Ends With A Heatwave

  1. Roland Derksen says:

    I’m thinking i’ll have considerably less than the half inch of rain I predicted for the 6th. The forecast seems to be just for showers- we need a steady rain.

  2. Mike says:

    Best weather of the year? Like sun is good and rain is bad?

  3. Weatherdan says:

    Latest 16 day gfs meteogram has PDX with .10 of precip. Yesterday it showed .22. And on Sunday it showed .55. My feeling is PDX gets maybe .05, and Salem and Eugene get at most a trace. Then more hot weather. Peace.

  4. Zach says:

    Once again the 6z tries to bring a low in to cap the temps next week (somewhat).

  5. tim says:

    Friday’s storm appears to be weaker with every model run and 00z gfs just verified that maybe 0.05 for seattle now instead of .30 a couple of days ago.

  6. W7ENK says:

    WRF-GFS has CAPE values over the N WV absolutely exploding tomorrow afternoon.




    Could be an interesting day tomorrow.

  7. W7ENK says:

    Baseball-sized hail reported from the thunderstorm just to the East of Bend. NWS Pendleton warned for quarter-sized.

  8. Zach says:

    It appears almost certain that the 11th-15th will be hot. The question is exactly how hot.

  9. W7ENK says:

    Fairly active thunderstorms just off the coast this morning, lots of ACCAS around the N WV. The sky is looking pretty bubbly this afternoon, and humidity is holding up pretty well. Could be an active afternoon? Probably just wishful thinking…

  10. Hank says:

    Hey I know it’s a little early, but this summer sucks so I’m looking forward to winter

    Can you make a post on the 2021-2022 la nina? I’ve heard it will be la nina, but you posting something on how strong it will be and it being 2 years in a row, would be a nice post everyone needs, to think about skiing.

    Please make it.

    • Anonymous says:

      He usually makes one after the yearly Winter Weather Forecast Conference at OMSI at the end of October! Winter can’t come soon enough

  11. tim says:

    I know I sound a broken record but tonight’s 00z gfs run is the hottest yet, geez.

    • Joshua Lake Oswego says:

      The 6z did a 180. 70sand 80s instead of 100s. Ridge axis centered further north and west allowing a low to slide right in to Oregon for some rain and cool temps. Will it verify? Heck no, but it’s nice to look at.

    • Zach says:

      Honestly with all the fire smoke we will have with the east wind, I think these temps would be impossible.

    • Anonymous says:

      What site do you use to see possible upcoming temperatures? Thanks!

  12. tim says:

    I think it’s clear were going have some kind of “heatwave” by mid august all models are showing that now, hopefully it will be the last one of the year.

    • Anonymous says:

      September and October are (as of now) forecast to be cooler than normal, so if this materializes then it should be the last of it until next summer.

      • Hank says:

        It was saying the same as mid July, I don’t remember seeing any significant heat wave, the models normally do that, just because it actually happened earlier this summer, doesn’t mean it will happen again, but I guess it is more likely to happen twice in one year, since we are in a pattern.

  13. Weatherdan says:

    88 at 2:30PM. On Our way to 93. 20% chance of maybe .05 on Thursday or Friday, then back to hot weather. This is what you get with climate change so get used to it. This will be our 29th day at or above 90 in 2021. We are on pace for 42 such days this year. As a child I remember some years had only around 40 days over 80 the entire Summer. Today is day number 65. Still by October we will enter our rainy season and things will return to normal. Or will they. Stay tuned. Peace.

  14. tim says:

    Gfs is showing around .30 of rain for my area with Friday’s storm nothing impressive but not bad either for the first week of august.

  15. Roland Derksen says:

    Whooa- what’s this? Water falling from the sky?? A few light showers are coming through my location this morning- have even heard some distant rolls of thunder. I don’t expect much more to develop, but at least it’s an intresting way for the month to end.

    • Roland Derksen says:

      Some more light showers here this morning, but skies are clearing. Due to yesterday’s measurable precipitation (0.01 inches) July 2012 is NOT my driest ever- it’s in 3rd place, behind July 1985 and July 2013!

  16. Joshua Lake Oswego says:

    So far, PDX is 1 degree off of the highest ever low temp this morning. 73 degrees.

  17. tim says:

    Gfs 18z is on fire at the end of the run, yikes.

  18. runrain says:

    Raindrops! Happy Valley.

  19. W7ENK says:

    Light rain and distant thunder just to the East of Estacada a little while ago.

    Looks like it’s clouding up at home, too.
    Methinks 100 degrees is off the table.

  20. tim says:

    Cliff mass new post about thunderstorms and a early fall like storm late next week which he seems amazed but the euro model is only showing a total of 0.07 rain for seattle via scott sistek twitter, I guess that’s a lot of rain for the first week of August apparently.

    • tim says:

      We all know cliff is a sensationalist I guess I shouldn’t be surprised we he gets excited.

    • Anonymous says:

      I’d love an early fall like storm. It would be a nice reprieve from the heat and a little preview of what could be coming this way in a month or two.

  21. Ken in Wood Village says:

    I see showers forming in the right spot and the direction they are moving will give us a good chance for showers and possibly thunderstorms 🤗⛈

  22. Andrew says:

    Definitely a haze in the sky today that suggests smoke to me, but perhaps just high level clouds. air quality reads seem generally normal.

  23. Zach says:

    Was there supposed to be heavy cloud cover out on the east side this early? If not than I think the forecast of 99F for Gresham today could be a bust coming.

  24. tim says:

    00z GFS has a nice little trough coming thro next week then a return to our normal hot august weather with highs near 100 at the end of the run, august is the hottest month of the year after all, anything less would be abnormal.

    • Anonymous says:

      12z flipped back to cool again. Weird how much its been oscillating between very different solutions.

      • tim says:

        I heard tropical storms and hurricane can effect model performance and models are showing some forming south of way south of California but I don’t know if there any truth too that I’m sure someone knows.

  25. Ken in Wood Village says:

    I’m getting ready for bed, I get up at 4am to get ready for work. I thought I would look at the radar in the Medford area. It looks like the flow is starting to be more North to Northwest now instead of North to Northeast. We’ll see if this is true when I wake up tomorrow.

    Have a good night. Maybe we will see thunderstorms in the morning…lmao. It’s happen in the past…hehe.

  26. runrain says:

    It just got really cloudy really fast.

  27. Ken in Wood Village says:

    I’m going to say, there’s a outside chance of getting a thunderstorm on the East side of Portland (mainly Sandy East, could be as far West as Gresham but the percentage is much lower). Friday and Saturday is looking better for thunderstorms for our area. SPC has put our for thunderstorms. We’ll see what happens. The percentage is low but I have seen it low before and get multiple strong thunderstorms. It would be nice to get some to cool off the atmosphere in the evening. Let’s hope for the best 🤞⛈

  28. Weatherdan says:

    99 at 3:35PM. 27th day above 90 this year. Probably will hit around 102 today. Not a record but still hot. Peace.

  29. runrain says:

    Pretty good batch of moisture seems to be moving up the valley, maybe just in time for max heating. Afternoon thundershowers? Very warm overnight lows tonight?

  30. W7ENK says:

    100% guarantee there will be thunderstorms with heavy rain in PDX metro this weekend. Why am I so sure? Because for the last several weekends I’ve been purging my back shed of all my old belongings, have pulled everything out into the back yard to go through it all and decide what to keep and what to toss. In that process, I discovered damage to the interior walls from rodents, which will require cleanup and fixing before I move stuff back inside. To add insult to injury, I dropped a sheet of particle board from the top of my shelving square on my toes and broke my foot last Sunday. Now that everything is outside, and I’ve been rendered gimpy… my landlord isn’t able to come fix the walls until NEXT weekend, at the earliest.

    That said, 100% guarantee there will be thunderstorms with heavy rain in PDX metro this weekend, because the Universe just loves kicking me in the bawls like that.

  31. Zach says:

    Last nights 12z & 6z GFS runs are both beautiful looking if you prefer mild weather the next 10 days.

  32. Lurkyloo says:

    Major earthquake off Alaska coast.

  33. Andy says:

    Looks like a slight chance of some Thunderstorms west of the cascades this weekend…any lightning would be a disaster if this happens with no rain. This could be the big headline or nothing at all…just something to be aware of.

  34. Anonymous says:

    Yeah….long, long time lurker. The weather info from Mark is amazing but there is some weirdness amongst the frequent fliers. Everyone chill about autocorrects, spelling and one person’s opinion. That’s obnoxious. Also, I’m no fan of a certain political party either but that too has no place. Aloha

  35. tim says:

    I see that there are a lot of sensitive ppl on here that get upset all because I made a statement or ask a question or even miss spelled a word that autocorrect did not fix, well then put me in front of a firing squad. im sure u Republicans would love that since ur all about violence aka Jan 6th.

    • Anonymous says:

      Typos and autocorrect happen to the best of us, don’t sweat it!

    • W7ENK says:

      Why even go there? That made absolutely no sense whatsoever, never mind the fact that it’s a violation of Mark’s #1 Rule up top, “No politics!”

      Regardless, I see your political feelers are about as astute as your weather feelers, you couldn’t have possibly been any farther from the target. Were you even facing down range when you fired that one off, or did you have your back to the bench??

      Jeezus bruh…

      • Snomanski says:

        Sadly W7 we live in a world in which merely stating facts is seen as a political act. Which, now that I think about it, it is.

        • Hank says:

          I’m going to try to make this the least political possible, this is a unbiased response,
          Yes Jan 6th and alot of the ones about the elec being rigged, but don’t say the other side isn’t biased too (cough downtown Portland last summer)

          but I shouldn’t have gone into politics, but what you said was sooooo unnecessary

        • Hank says:

          Uhg auto correct….. I’m just going to type the whole thing again but fix what auto correct shouldn’t correct….

          I’m going to try to make this the least political possible, this is a unbiased response,
          Yes Jan 6th and alot of the other protests about the elec being rigged was bad, but don’t say the other side isn’t violent too (cough downtown Portland/seattle last summer, cough chop)

          but I shouldn’t have gone into politics, but what you said was sooooo unnecessary

  36. Jake says:

    I’m going to say it for myself here and I know I sound whiny.

    I’m ready for Winter. I’m tired of the dust, tired of the smog, tired of the smoke, all the dead and dying vegetation and I won’t even go over the humidity at night that we normally don’t see.

    It has been Summer since the end of March. Sure we have cool mornings but this heatwave has more just, bored me out of my mind about weather. Apart from the Winter events end of February? What a super slow year.

    I thought I liked sun and could handle moving further South. Heck, no. I can’t remember the last time I smelled a pine needle or just fresh air. Everything outside smells like dusty dirt.

    • W7ENK says:

      Whoa, Nelly… Slow down there son, you skipped right over Fall!

      • Jake says:

        I forgot my potted palm tree in the sun during the extreme heatwave and also to water it. It is on its last legs. I’m mad. All my potted plants didn’t stand a chance. Baked dirt vegi. pie.

        • W7ENK says:

          Palms should be able to handle 115 degrees. They’re all over in Phoenix, and temps on the North side of 100 is a regular day for them mid June thru early September.

      • Michael Gelien says:

        I am being making it look like its been raining around my place. Irrigating as much as I can to increase the water content of our trees in case of fire. Going so far as to wet down the gravel drive to keep the dust down too.
        Love the green happy trees in spite of the drought.

    • Anonymous says:

      Hopefully Pete Parsons’ seasonal climate forecast holds true and we do in fact see cooler than normal September and October. I’d be glad to see the 90s and high 80s stay in meteorological summer. And I’d love if winter didn’t wait until late January and February to show up this year like it has the past few. We’re due for some December snow.

    • Roland Derksen says:

      Hang in there for just a little while longer- cooler temperatures and cloudier skies are coming next week. i know it’s been difficult with all the heat and dust. If you were to come further north where i am, you wouldn’t see much of an improvement. We’re all in this together, but eventually it will pass.

  37. tim says:

    Yikes 12zgfs has another run at 100 pulse at the end of the run for both seattle and pdx not to believed tho. it seems the the gfs has been over doing the heat long term, when is the next upgrade?.

    • W7ENK says:

      “Overdoing…” lol

      So tell the class, Tim. Last month when GFS was showing 118 at PDX in the long term, and PDX verified at 116F, how “overdoing” was that?

      And are you deliberately typing “pulse” or do you actually think the word “plus” has an E at the end, and you’re getting autocorrected? Either way, it’s obnoxious. Stop it.

  38. Roland Derksen says:

    I’m sure this will at least be my 3rd warmest July, might even make it to number 1, if the temperature trend for the next few days holds. It’s not so much because of warm daily maximums, but because we just haven’t had any cool ones- usually in past years , I could count on a few days in July (3or 4) where the afternoon high doesn’t exceed 70 F.

  39. W7ENK says:

    Over the weekend I drove up to N. Vancouver (Salmon Creek area) to visit family. Heading up I-205, I could plainly see how burnt the trees are on their South and West sides, particularly the Douglas Firs. They’re a copper orange color! This was especially evident on the North side of the river. So now, a month later, we know for a fact that Dougies can’t handle 115+ degree heat.

    It will be interesting to observe through the Fall and Winter, and into next Spring and Summer just how badly these poor trees have been affected. It could be that they’ll simply shed their singed needles and add new growth next year… or perhaps they’re in their death throes?
    Hoping desperately for the former!

    • Lurkyloo says:

      I notice that, too. I’m on the Airport Max everyday and those poor trees look so hurt! News article said they were “scalded.” I’ve also noticed that oak trees aren’t fully growing acorns? Seems like they grow a little small acorn and then it just falls off.

  40. tim says:

    I see the crazy and unreliable 18z gfs is given us some rain at the end of the run.

    • Zach says:

      The precipitation signals have been increasing though. That and the SW monsoon is now extended way north towards eastern OR. Have a feeling we will see rain in August, although probably from convection.

  41. tim says:

    Weather.com and underground are showing 102 for pdx Friday, of course that’s raw data with no human input I assume.

    • Joshua Lake Oswego says:

      Well, the GFS are Euro are both over 100 and it’s only two days away, so I would say it’s a safe bet.

      As I have said many, many times… high pressure always increases in intensity and duration as it gets closer in time.

  42. Anonymous says:

    Your weather blog is the best and most complete around. Thanks for the great work!

  43. fatherscottb says:

    I assume, Mark, that during the mini-heat wave that the dew point will be really low, so not very humid, even at night?

  44. W7ENK says:

    Okay, well…

    Per the official definition for our local climatology, today officially established a “heat wave” in Milwaukie. Third day in a row at or above 90 degrees. At this point, it’s likely going to continue into next weekend.

    I’m ready for Fall.

  45. tim says:

    We’ve been lucky this month no big heat waves yet, well there’s always august to make up for lost times, that hot ridge has been just to the east of us so far this summer I wonder if it’s gonna move over the top of us before fall arrives.

    • Anonymous says:

      haha you never give up do you

      labor day weekend is usually when summer ends with a bang. you’re not wrong… there’s still time but the ridging is weakening.

      for the event youre describing, the ridging would have to move back west over the cascades and rebuild strength. seems unlikely.

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