Longest Hot Period Since 2009 Ahead, but Probably No Extreme Temps

Our longest heat wave/hot spell since 2009 is in the works this morning.  That was the year we hit 106 two days in a row and broke a record for consecutive 90 degree days…10 days!

The bad news?  We likely have a long period (7+ days) of 90 degree or higher temps on the way, the longest since 2009.

The good news?  At this point it doesn’t appear we’ll get much above 100 degrees, if at all, so at least it won’t be too extreme.


1. Hot weather (90 or higher) begins on Friday and appears to last THROUGH MOST OR ALL OF NEXT WEEK!

2. Hottest temps are likely Saturday, although Friday and Sunday will be close.  I think we may just touch 100 degrees Saturday, or it could be another one of those 99 degree days like last summer…we did that twice.

3. With a lack of dry east wind, it’s possible we get into a humid situation through this heat wave.

4. That lack of dry east wind also means it’s unlikely we get the really extreme temps…like 102-107 degrees, that we often see in shorter heat waves.

5.  We may (or may not) see some thunderstorm action either Sunday or Monday, right now only one model is showing that setup.

For the hard-core weather groupies:

I had yesterday off to do some things with the family and the bizarre “July in June” weather was great!  My garden is the best it has ever been this early in the year due to the abnormal heat.  The funniest part of the weekend was Sunday when I was looking for an air conditioner for my elderly parents (thought it would be bad if the weatherman’s parents were suffering in the heat).  My kid’s say “hey, your forecast is on all the fans!”.


Sure enough, the Home Depot in Troutdale was using our forecast to pump up those sales!  Good stuff, and I’m confident they will be gone within a few days.  Too bad I don’t get some free decking lumber in exchange, but that would be Payola.

So I’ve perused the maps and models and two thoughts come to mind.

1. This is going to be a long period of very warm and/or hot weather.  I don’t think we’ve seen this since the summer of 2009.  Take a look at the ECMWF ensemble chart from last night’s run:


Of course this is temperature around 5,000′ in celsius.  The green line is average for this time of year.  At no time (except this morning) does the airmass temperature get down even close to normal in the next 15 days!  That’s the ensemble average red line…a collection of a bunch of runs.  But wait, there’s more.  From later Thursday through the 6th of July (about 11 days) the temperature is +19 or higher…wow!  Generally that’s around 90 degrees or warmer.  If at any point easterly/offshore flow develops, the temp would go much higher.  The 00z GFS ensemble chart looks like this:


It’s not quite as extreme with the temp going down a bit more, but still a long very warm/hot period.

Why so long?  Models have a hot ridge building quickly Thursday/Friday with the core of the heat (center of the ridge) centered close to Boise/NE Nevada.  Check out the ECMWF ensemble 500mb heights for this Saturday:


A scorcher for the entire west.  Hate to be in Boise this weekend!  IF the ridge was to be centered directly over us, as models had shown late last week, we’d be a good 5-10 degrees hotter.

Now notice what changes by the 4th of July (on the ECMWF):


Not quite as hot, but still it prolongs the heat wave.   The ridge is trying to pop up back in its preferred position this past fall/winter/spring…a bit to our west/northwest. I noticed the operational run of the ECMWF has 500mb heights above 588dm from Thursday PM through the following Thursday…a very long period.  Other models are similar but with varying details of course.

2.  At This Point Extreme Heat Looks Unlikely

Your first thought is likely…”what does Mark consider extreme heat; sure looks like it to me“.  I mean 100 degrees and beyond.  As of this morning, models are not showing offshore (easterly) flow except briefly (and weak) Saturday morning.  For our extreme heatwaves in the past, where we see several days in the 102-107 range, we get a sharp thermal trough of low pressure west of the Cascades (in the valley or even at the coast) and gusty easterly wind through the Gorge and over the Cascades.  Because the upper-level ridge is centered to our east, the thermal low is as well.  I remember learning that way back around 1992…in fact I think George Stephan taught me that the shape/position of the thermal low/trough is usually similar to the ridging and I’ve noticed that over the past (shudder) 23 years since that time.  To get a sharp thermal trough westside (and extreme downslope heating) you need a ridge right overhead or to our north (90% of the time).

To make a long story short, we’ll have weak onshore flow during most of this hot spell.  That may lead to another unusually humid hot spell too, we’ll see.

As for thunderstorms, the setup could be right Sunday or Monday, but the ECMWF and GEM don’t show any moisture for storms so I’m not real excited about that possibility right now.

Chief Meteorologist Mark Nelsen

86 Responses to Longest Hot Period Since 2009 Ahead, but Probably No Extreme Temps

  1. JohnD says:

    Maybe a bit of a t-storm back down albeit amid a wavering pattern(?). I personally prefer an honest heat event without them. Fire season being the biggest concern. We’ll see. Plus we are trying for the Middle Sister summit on July 4! So for personal reasons too…..

  2. Hal in Aims says:

    about 2 dozen quarter sized sprinkles earlier this afternoon while mowing………..pretty evening…….probably the last for a while…….

  3. Jason Hougak says:

    Bring on the thunderstorms⚡️⚡️⚡️

  4. WEATHERDAN says:

    85 at 3:00 PM. No rain today but lots of clouds earlier. Should hit 87 today. Would have hit hit 90 without them. Except for low 90,s on Sunday we might see 12-15 consecutive day in the mid 90,s or hotter. Looks like we have a good shot at hitting 100 again by Next Wednesday or Thursday. In 1967 we had an August heatwave that had temperatures at 96-99 for ten consecutive days. This looks longer and hotter that that. In addition the heatwave in 1967 was close to the end of Summer. Now Summer has just started. Conversely many places that saw a very cold and snowy Winter last year look like they will have a cool and wet Summer. Our pattern seems to be stuck. Yes it could change in an instant. It just doesn’t appear likely any time soon. Peace.

  5. W7ENK says:

    307 PM PDT WED JUN 24 2015


  6. David B. says:

    It’s been sprinkling up this way for at least an hour now. Not even enough to wet the pavement but it has caused cooling. Was up to 75 when it started, now 69.

  7. 12:35 PM Visible Satellite Imagery
    2 KM VIS Loop http://sat.wrh.noaa.gov/satellite/alternative.php?wfo=pqr&area=west&type=vis&size=2
    1 KM VIS Loop http://sat.wrh.noaa.gov/satellite/alternative.php?wfo=pqr&area=west&type=vis&size=1
    I am utilizing the 2 KM resolution to really show what’s going on. Typically we use the 1 KM as it’s more localized, but it doesn’t paint the best picture for today. Running the loop shows the most extensive cloud cover occurring now through about 2 PM in my estimation. We also see decent clearing now along Coast and the offshore waters cloud cover is starting to dissipate with thinning higher clouds. 1 KM Loop shows this nicely now. There is also a small finger of stratus near Cape Blanco. I believe we should be clearing out by mid afternoon. The reason we are seeing the unexpected thicker cloud cover and sprinkles today is the ridge is quite flat and the shortwave offshore pushed a lot of cloud cover over in west to east flow. 8KM Water Vapor Imagery shows the upper level pattern the best. If we wanted good clearing we’d want to see more of a southwesterly or southerly component to the flow, but with the ridge not yet building in that isn’t the case today.

  8. 12:01 PM 6/24/15: Update
    I just analyzed today’s 12z WRF 4km PDX Sounding. Offshore flow is a bit weaker on this run, so may have to back off a few degrees perhaps 100-103.

  9. alohabb says:

    And now it’s raining. In Beaverton.

  10. alohabb says:

    Hey, what’s going on…. No sun today ?

  11. W7ENK says:

    Head Jaanipäeva!!

  12. schmit44 says:


    Deadline to enter will be Thursday night at midnight. The program has the current NWS forecast numbers in the placeholders.


  13. W7ENK says:

    So, no go on the 112 degrees then? :-/

  14. schmit44 says:

    Put this chart together this morning with the estimated records to be broken this month. We have never seen all-time records get broken by this much of margin before.

  15. Garron near Washington square says:

    Almost looks like a pineapple express heading our way. This will moisten the atmosphere up nicely! Already 70 degrees out there, and starting to feel down right tropical! Nice to see Mark has so many “fans” out there, lol.


  16. Jason Hougak says:


  17. Lee Wilson says:

    I just would like to inquire about an incoming system I see building to our west in the Pacific Ocean area.

    What effect will it have when it hits our area and will it be hitting before the heat starts?

    Just curious. .that is all..

    • Eugene Dave says:

      If it hits, there’s a good chance of rotten pumpkin. Also possible for a large mold outbreak in any greenhouses in the area. Expect solar panels to send energy back to the sun.

    • Lee Wilson says:

      If I have to send energy back to space, I have to charge the government . and then they have to charge the taxpayers.
      For “Deflection Fees”.

      Then I will have to write up a bill for the IRS tax proposal of oh lets say 15 percent tax. t replace pumpkins and green houses effected.

      hmm I will need to add some pork to that too to make sure it passes.

    • Lee Wilson says:

      Actually very is what happened all ready in the 80 degree weather.

    • Lee Wilson says:

      Yes that plant with the large bead leaf making its way out of the greenhouse is a pumpkin ..it..is..becoming a monster..

      Oh that reminds me..
      Mark, what’s the word on man eating plants?
      Where weather deserves weird plants …right?

  18. **** Extreme Heat Saturday: 101-104 degrees or even hotter? ****
    Based on what I’m seeing I’m going all-in now. I’m doing what I have done many times in the past, I’m going out on that proverbial limb and thinking we could be in the low 100’s or even hotter now. Why? 850mb temps are going to be very warm modeled at +25c or so, IR Model shows only some high clouds in the morning hours and then mostly sunny or clear skies from 12 PM – 6 PM during max heating hours. The most important factor is offshore flow. 00z WRF 12km PDX Sounding shows offshore flow develops aloft by Friday night. It’s not real strong around 10-20kts, but you don’t want it to be either.

    Saturday morning 3-6 AM it increases slightly around 15-25kts below 2000′, then lightens up to 5-10kts even mixing down at the surface through about 2-4 PM. That is ideal light offshore flow just enough downslope component to push us well over 100 degrees. Unless model runs tomorrow back off this, but I don’t think so. The only thing I’m slightly leery of is convection Friday evening and how much debris cloudiness if any will be lofted north into the valley and how persistent will it be. We really don’t want any storms to develop down south at all to ensure full on sunshine Saturday. I guess we’ll find out.

  19. schmit44 says:

    00z operational GFS showing a historical 14 consecutive days above 90°. The current record is 10 days set back in 2009.

  20. 00z GFS looks hotter for Saturday with the thermal trough a bit sharper…… Otherwise how does potentially 14 days of 90+ degrees sound? Sounds awful to me, yet if this run is right it may occur.

  21. schmit44 says:

    6/23/2015 Oregon (All) Temperature Summary

    High:96 at Rye Valley(I-84(2230 ft)
    Low: 70 at Rye Valley(I-84(2230 ft)

    High:56 at Newport(30 ft)
    Low: 29 at CROW FLAT (5172 ft ) & KIRK (4519 ft )

    Largest Diurnal Change: 51 degrees
    EW6078 La Pine (83/32 ) (4259 ft )

  22. Jason Hougak says:

    Mt. Hoods glaciers are already taking a toll from lack of snowpack to help it through summer, this heat is just gonna add insult to injury. Better take as many pictures now of our majestic Cascade peaks, the glaciers won’t be lasting much longer.

  23. Jason Hougak says:

    Like my sense for snow, I have a feeling we’ll get thunderstorms. If they are dry then you can bet some fires will be started.

  24. Boring Oregon says:

    Noo! Mark took the t-storms out of the 7 day forecast! POO

  25. I appreciate the update on the heat wave, Mark! At my location, I can expect it to reach 93 or 94F- that’s hot enough for me! I didn’t like the 98F I saw in late July 2009.

    • David B. says:

      NWS is going for 83 on Saturday and 82 on Sunday for my location. It’s hard for me to break the 90 degree mark (too much nearby cool salt water), but I think that still sounds a little low. I’m thinking more like mid-80s this weekend.

  26. WEATHERDAN says:

    What a really nice day we have. 80 going to 86, A nice Northerly breeze and wall to wall sunshine. Some Junes are pretty abysmal around here. But we sure have lucked out this June. Then again it has been really nice all year long so far. And hey look on the bright side. Most years the blog is really slow this time of year. Now we have something to talk about. I am looking forward to this heatwave. If you stay hydrated and keep strenuous activity limited and between about 9:00 PM to 9:00 AM then the heat will be an annoyance but nothing more. Please be sure to look in on the elderly and the infirm. Peace.

  27. I guess I’m one of the few people who loves the heat… but then I’ve always felt like I shouldn’t have been born in the NW. The only thing I will complain about is missing the central AC in the house I just moved from. It looks like I need to go buy a portable one. 😦

    • Paul D says:

      Better get it NOW! They’ll probably be out of stock at the stores and on Craig’s List this weekend for double the normal price!

    • David B. says:

      If you “love the heat” why do you “[miss] the central AC”? Doesn’t make sense.

      I’m not a big fan of AC unless it’s humid or REALLY hot. It just ruins my heat acclimation and keeps me indoors. Last year I was doing botanical surveys on the east side of the Cascades, 95 to 100 each afternoon. Then I came back to my paid job and the air conditioning was just soooooo cold!

    • Tracy Anderson says:

      David B. — sorry I didn’t see your reply earlier. The reason I miss my AC is because I have 3 English bulldogs. In case you don’t know, flat-faced (brachycephalic) dogs are heat intolerant. Bulldogs can get heat stroke with temps even in the 80s… my house was 85 degrees inside. It took me 2 days to find one, but Coastal sold me their display unit AC. My dogs are comfy & happy now… and I’m cold. lol

  28. BTW….91 days till Fall 2015.

  29. Tyler Mode in Battle Ground says:

    Here are photos of the aurora from last night. This gallery is best viewed in slide show mode so you can get an idea of how the aurora were dancing across the sky! (You can use the arrow to progress faster if you’d like)

    Excuse the repositioning of the camera a few times to capture the best lights!

  30. Benjamin (West Salem) says:

    Hoping for some decent thunder storms with this heat.

  31. alohabb says:

    I can’t believe this, but my upcoming trip to Kauai is going to be a blessing to get away from the heat!

  32. Joshua says:

    Goodbye to anything that is still green. Is it November yet?

  33. 12z GFS high temperatures. *Taken at face value according to raw data. This is NOT a forecast I’m giving. :: June 26th – July 4th ::

    FRI 95, SAT 101, SUN 98, MON 96, TUE 92, WED(July 1st) 92, THU 94, FRI 101, SAT(July 4th) 98.

  34. Tyler Mode in Battle Ground says:

    I’m ready for fall…

  35. Thanks for the detailed update, Mark. We agree with you definitely

    6z GFS Ensembles – 6/23/15
    (*All credit to Jim Little)
    Hot to very hot. Ensemble mean peak +26c. The majority of members are in the +20c to +24c through the 4th of July holiday. Real potential for a prolonged hot spell.

    12z GFS – 6/23/15 …. Hot to very hot 95-100, but not extreme heat(100-105+), brief “cool down” and then upper heights rebuild with hot weather returning July 2nd through the 4th of July holiday. Again, as Mark explains real potential for a week of 90+ degree weather.

  36. “At least that one wasn’t too humid (lot of offshore flow)”…the August 1981 event that is.

    • runrain says:

      Wasn’t that the one where it hit 107 deg and was forecast to be even hotter the next day but wasn’t because of the moisture streaming up from the south? 102 that next day as a result with high clouds almost the full day. I think it was 1981. I actually do remember the 107 in 1967, I believe it was. Just after the flood of 1964 and Columbus Day storm of 1962. Nice five year run of weather, there!

    • WEATHERDAN says:

      I do believe the 107 was in 1965. Saturday July 31st to be exact. I do remember that day well. It hit 104 in Salem that day after hitting 103 on Friday the 30th. And yes there were high clouds that knocked a couple of degrees from the high on the 31st. Then on Sunday August 1st under sunny skies the temperature reached 75 by 10:00 AM and stopped there. The ULL off of the Southern Oregon moved in and initiated a strong marine push. By 5:00 PM it was only 65 in Salem. Peace.

    • W7ENK says:

      107 @ PDX, August 8 and 10, 1981.

      I don’t remember it, I was 2.

    • W7ENK says:

      Before that: July 30, 1965

  37. Wonder how many fires we’ll see over the 4th of July…..Will be SO dry. Just don’t want a repeat of the early August 1981 heat wave please or the 2009 one either. At least that one wasn’t too humid (lot of offshore flow).

    Nights are going to be real sticky if all this comes to fruition. 😦

    • Not like it will make a huge difference cause everything’s already so dry, but won’t humid weather help a little as far as fires? I know the dry east wind makes things a lot worse for fire hazard.

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