The Great 2015 Northwest Heat Wave; A Historic Weather Event

We are suffering through the longest heat wave we’ve seen in at least 75 years west of the Cascades.  Does it live up to the title billing of THE GREAT 2015 NORTHWEST HEAT WAVE?  I feel that’s definitely a YES in the lower elevations of SW Washington and NW Oregon.  Likely it’s the same in many other locations as well.

I had a lot of free time this evening since it’s a Sunday and we only have one show at 10pm.  So I took an hour and looked over past records for the Portland area.

Where the heat wave stands right now

  • Today is our 7th consecutive 90 degree day in Portland (all-time record is 10 days from 2009)
  • Today is the 5th consecutive day at/above 95 degrees! (not a record, we’ve seen 5 100 degree days in the past!)
  • 10 out of the last 11 days have been at/above 90 degrees
  • Today is the 14th day this summer above 90 degrees (we’ve passed our yearly “allotment” on July 5th)

* Note I’m calling this a heat wave (singular) because of the duration.  We only ended up with one day down at 85 degrees.  Looking back I’m quite confident we’ll look at it as one long event.

Our 7 Day forecast looks like this right now:

7 Day

Note that we PROBABLY have 4 more days in the 90s before the well-advertised cooldown at the end of the week.

Assuming we stay above 90 degrees as forecast, by Thursday evening it should look like this:

11 consecutive 90 degree days (A NEW ALL-TIME RECORD)

14 of 15 days reached 90 degrees or hotter (Unprecedented in Portland history)

18 – 90 degree days for the season…ALREADY BY JULY 9TH!


I have looked all the way back to 1940 in airport weather records (official observations) and can not find a similar duration of hot days; or anything close to it!  Now add the fact that warm overnight lows have been breaking records right and left (6 tied or broken so far).  This is a truly historic hot weather event for our area.  Not the hottest heat wave we’ve seen, but the longest.

Remember our “greatest heat wave” in 1981?  Yes, 4 days at/above 100 culminating in a 107 twice!  Or the July 1941 heat wave when we were above 100 for 4 days!  Even in those events, cooler weather (60s-80) preceded it or followed soon after.  This time it’s just been one long continuous warm spell.

There are two heat waves that attempt to come close to this one…

JULY 1985:  10 days 85+, but no more than 3 consecutive days above 90 at a time.  22 consecutive days;  only 2 were below 85!

AUGUST 8-22, 1967:  8 days 90+, 15 days 85+.  But all nights were 60 degrees or cooler…much more comfortable

By the way, you may be thinking of some other heat waves.  Wondering if I missed your favorite?  Here are 2 others that were quite impressive.

JULY 2009:  10 days 90+, then quickly down to 60s/70s for highs!

AUGUST 1992:  A hot month, 10 days 85+, but cool just before and after

AUGUST 1972: A hot 10 days, 7 days 90+, but cool just before and after like 1992

Have you noticed one thing has been missing?  No 100 degree days (in Portland).  In fact we haven’t been above 97 which is very strange for such a long period of hot weather.  This is the 2nd summer (so far) in which we are not seeing sharp thermal low pressure troughs develop west of the Cascades; sending a hot east wind down into the valleys.  That’s when we go above 100 degrees.  Those are often followed by a dramatic cool down as well.  Interesting that we’ve had upper-level highs consistently over us for a hot atmosphere both years, but very little amplitude to the flow to give us brief offshore flow.  We’ve been doing much of this heat with weak-moderate onshore flow.

So you’re sick of the hot weather and wanting a cooldown right?  I think most of us are. We definitely have one for next weekend, but it remains to be seen if it’s just a brief cooldown and hot weather returns the 2nd half of the month.

Chief Meteorologist Mark Nelsen

46 Responses to The Great 2015 Northwest Heat Wave; A Historic Weather Event

  1. David B. says:

    Today’s 78 degrees was the first sub-80 high in I can’t remember how many days. It felt almost autumnal.

    • Boydo3 N. Albany says:

      86 deg. today for a high at my house. First day in way too many days above 90. Nice coast breeze kicked in this evening too. Ahhh….

  2. Lee Wilson says:

    Solar has been doing well.

  3. Tyler Mode in Battle Ground says:

    Pretty chilly today here in Battle Ground. Only 89 degrees! Only a 5 day streak of 90+, with 1 day at or above 90. Being in the suburbs makes a difference!

  4. Boring Oregon says:

    Just looked at lightning and it showed a lightning strike just to the south of Hillsboro. Not buying it.

  5. Paul D says:

    Mark: I like how you started that out with the word “suffering”. That definitely describes this weather!

  6. Natalie Schmotzer says:

    What about Salem? At my house we have been hitting 100 to 103 most days this last week.

  7. WEATHERDAN says:

    86 at 1:00 PM. The maximum today should reach the mid 90,s. Another hot week at hand but thankfully not as hot as last week. Then a break into the low to middle 80,s starting Friday and continuing into early next week. Then a slow warmup to around to around 90 by the following weekend. But no sign of any extreme heat coming up. So far in this heatwave our hottest days in Salem have been.100, 100, 99, 98, 97, 96, and 95. This heatwave if you consider the minimums and maximums together are around 4 degrees than in 1967. But since it was in mid to late August in 1967 and late June and early July this time the longer days means the daytime heat starts earlier and ends later. This is the best Summer I have ever experienced in my 61 years. All of them in Salem. We could see 3 more months of really nice weather. Peace.

    • High Desert Mat says:

      Funny, Mark has upper 70’s for his forecast starting this weekend. Its going to feel nice out there.

    • WEATHERDAN says:

      NWS just called for 80-85 Friday-Monday in Salem. Mark might have a different forecast but his is not the only forecast out there. Also Mark’s 7 day forecast is for PDX and not SLE, There is sometimes a 3-5 degree difference in temps. As an example PDX has gotten no higher that 97 during this heatwave. SLE has hit 100 and EUG has hit 101. So forecasting for one location does not fit all. I know mat how you like to say SLE is a suburb of PDX but that is not the case. Our weather can be radically different. So this weekend PDX might be 78 and Sle might be 81. If you knew as much about meteorology as you purport to know I wouldn’t have to point this out to you. 90 in SLE at 3:00 PM. Peace.

    • High Desert Mat says:

      Geez relax. I’m just ruffling feathers. I’m aware of all that.

      In the meantime, temp just dropped 15 degrees in ten min here with a torrential downpour and lots of lightning.

  8. Sifton says:

    BEST SUMMER EVER!!! 100 more days plz…..


  9. Lee Wilson says:

    I am 45 years old, and I remember only one time when it was in 80 or 83 or so when we had horses being bathed at the Cowlitz county Fair grounds.

    They had to then turn on the massive cooling fans.

    But then some where in there we had 3 and a half feet of snow that followed. .

  10. runrain says:

    Flew cross country yesterday (Boston-PDX) and it was cloudy almost all the way. Some large boomers around ND that we had to dodge. At 40k altitude, I saw some of them building up through their anvil tops to higher elevations. These must have been of the severe variety.

  11. Farmer Ted says:

    I’ve been in the Portland area 61 years and this seems to me to be by far the biggest heat wave ever, and exceptional because it is so early in the season. I remember a really hot dry summer in 1967, then the hot August of 1981 where we hit 110 here on the farm and only matched that again with a 110 in 2009 (while I was gone for a week to Idaho), lucky to miss most of that one.

    Side note, I caved in and dad to order a ductless mini-split heat pump for my home, so we will probably have a rainy cool summer after this week! LOL!!!!

  12. I’ve seen 11 staright days (and counting) of 80+ degree daily maximums in my area- so that’s a record. However, that hardly matters now- it’s so smoky! Yesterday afternoon despite a brisk breeze, I couldn’t see the local mountains. This morning I could barely find the sun in the sky. It smells like an ash dump.

  13. David B. says:

    Blecch, smoke from some of the big forest fires in BC is now here. Gonna be a long hot smoky summer.

  14. alohabb says:

    The corn is already 7′ tall, the business has never been better,the pool is heated perfectly because of the sun… What a fantastic summer with 2 more months to go!

    • runrain says:

      Amazing. My tomatoes are approaching six feet. I’m wondering if I should prune the tops back to enrich the fruit.

  15. Paul D says:

    Below 80, please!!!! We deserve it. Everybody I talk to about the weather is really tired of the heat.

  16. Shannon says:

    Hi Mark, I am just wondering why my Fox 12 weather app shows different high temperatures in the upcoming forecast than your 10 o’clock news forecast? My weather app has the high temperatures for Friday, Saturday, and Sunday as 86, 85, 86. I saw on the 10 o’clock news forecast that the high temperatures were 85, 78, 80 for those same three days. I am hoping for the news forecast temps!
    Thanks, Shannon

    • Mark Nelsen says:

      Is that the FOX12 Weather app or FOX12 Oregon app? One is weather only and the other is news with weather as an option. That’ll help if I know which one.

    • Shannon says:

      It says Fox 12 Wx under it, and it only shows weather so I think it is the first one.

    • codegarden says:

      I’m seeing the same thing on the Fox 12 Wx android app: Fri 85, Sat 86, Sun 84, Mon 86, Tue 86… Cooler than the 90s, but not nearly as nice as the forecast I see on the website.

  17. schmit44 says:

    7/5/2015 Oregon (All) Temperature Summary

    High:104 at BLALOK( 277 ft) & ECHO(683 ft) & EW1140 Umatilla(364 ft)
    Low: 78 at ECHO(683 ft) & LAKE OWHEE AND O(2400 ft)

    High:58 at Port Orford(0 ft) & YACHTS Yachats(82 ft)
    Low: 41 at MCKENZIE (4770 ft )

    Largest Diurnal Change: 47 degrees
    COLGATE (93/46 ) (3231 ft )

    Heaviest Rainfall:
    1.17″ at WAGONTIRE(6420ft)
    0.93″ at SELDOM CREEK(4875ft)
    0.66″ at HOWARD PRAIRIE D(4299ft)
    0.62″ at COFFEE POT FLAT(5206ft)

  18. SwittersB says:

    Curious why you only go back to 1940 Stats?

    • Mark Nelsen says:

      Good question. Airport records began in 1940. Before that time records moved around between downtown (several locations) and Swan Island airport. All of those were on roofs. Between the hot roof issue and differing locations, I think it’s an apples vs. oranges issue.

  19. Also noteworthy: It’s earlier in the year than other significant events. This began in June…

  20. Tyler Mode in Battle Ground says:

    Finally getting around to posting pics from Glacier National Park in my 2nd gallery.

  21. I’m having a bit of a discussion on FB with a friend about the last time it rained. I distinctly remember no more than 2 weeks ago some downpours popping up over Longview, I know cause I was caught in one at work, but none of the moisture fell at the airport, I know we’ve had a couple days with T-storms, but nothing seems to have fallen at the stations. He’s trying to recall the last widespread rainy day.

    • Mark Nelsen says:

      It was Rose Festival Junior Parade day…Wednesday June 3rd. That day there were lots of showers from Portland north. It was the last measurable rain at PDX.

  22. W7ENK says:

    I’m lovin’ it!!

    • Mark Nelsen says:

      My garden is nuts! Never seen things grow even close to the speed they are growing this year with hot days and warm nights. Looks like early-mid August out there.

    • Boydo3 N. Albany says:

      This incessant heat is starting to remind me of when we used to get day after day of rain….remember those years? Winter doldrums, whining, complaining, wishing for a dry day…Ah..the good ol days.

    • W7ENK says:

      This time of year, this weather — THIS is why I survive our crappy winters here. Just a distant memory now, but it’ll be back all too soon…

  23. WEATHERDAN says:

    How sad is it if we get down to around normal or a few degrees above normal. (NWS is calling for 80-85 Friday through Sunday). And we call it a cool spell. Even so 80-85 sure would be nice for a few days. I have no doubts that we see 85-90 By the 15th and some low 90,s by the 20th. But probably not like what we are going through now. I do feel that we will have at least one more week or longer heat wave before summers end at the end of September. 96 today but already down to 85. Peace.

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