Heating Up

Most 100 Degree Days Happen in July Here in Portland

Most 100 Degree Days Happen in July Here in Portland

For those of you that have been living here quite a long time, the numbers in the image probably are no surprise.  We don’t tend to have all that many 100 degree days in August, especially after the first week or so.  Mainly because it gets tougher to overcome the longer nights and their associated cooling by mid-August.  By the way, two of those August 100 degree days were from last year.

So what’s new tonight?  Not a whole lot, except it’s obvious that we get no significant offshore flow until Tuesday AM at the earliest.  That’s why I lowered the numbers in the 7 Day forecast for Sunday and Monday.  The heat wave is most definitely still on the way, but it starts a bit more slowly and may not be a historic one.  I’m still real confident that we’ll see 5-7 days at/above 90 degrees.  As for whether we get to/above 100 degrees, we’re going to need at least SOME light offshore flow.

A new twist to our little heat wave is the dewpoints/humidity.  With the upper-level low closer to us tomorrow and Sunday, we add some moisture to the airmass.  Plus with no decent onshore OR offshore flow through at least Monday, we’re not going to get much mixing.  Overnight lows are headed up between 65-70 degrees and dewpoints should jump up into at least the lower 60s.  Looks a bit sweaty Sunday and Monday at least.

Try to stay cool over the weekend!

Chief Meteorologist – Mark Nelsen

455 Responses to Heating Up

  1. muxpux says:

    what heat? friday and saturday it hit 82 here in Longview, yesterday hit 88.

    right now its 63 and foggy. lamest “heat wave” ever up here.

  2. Snow-Zone/Monmouth-Elv200' says:

    7:00 A.M. 65.3F, over 100F guaranteed for today.

  3. Snow-Zone/Monmouth-Elv200' says:

    My low 63.3F now sitting at 64F….. probably need a frost advisory because its cold….lol

  4. Low so far is 60.3°, about a +3 from yesterday.

  5. PaulB/Eugene says:

    Most locations about 5-10 degrees warmer than 24 hours ago. That, in combination with offshore flow developing this morning (PDX-DLS gradient was +2 is now 0 and will be negative soon, EUG-RDM is already negative) most locations should reach 100-103F range.

  6. K5mitch NE PDX says:

    67.8 yuk…

  7. Tyler in Hazel Dell says:

    5 AM…69 degrees…will likely fall to around 66 or 67. The next few nights will likely be 70+

  8. Timmy_Supercell (Hillsboro) says:

    Salem is still 76 degrees! Unusual warmth tonight.


    • Matthew says:

      3am and its 73f at Pdx. Going to be really close if we are going to stay above 70f tonight.

  9. Timmy_Supercell (Hillsboro) says:

    69F in Hillsboro. DARN IT, there goes my competition… Cooler as usual.

  10. Tetra says:

    73.9F and good night.

    Who’s turn is it to take out the blog rooms trash in the heat this time?

  11. Tetra says:

    Matthew, I remember being in an old rental on Church Street (Silverton) and it would always be very miserable in the house like the lower 80s (Inside) and then around 3-4am a push of cooler air will come all at once.

    I mean it was just like someone threw a switch and cooler air came till the sun rose which gave a few hours of relief in the late 90s/early 2000s..

  12. Matthew says:

    76f as of 1am for PDX.

  13. Matthew says:

    I-205 as of 12:30am is still 75f.

  14. Matthew says:

    No sleeping for the next 3-4 hours intill it cools off around 3-4am. Then maybe 4 or 5 hours while it is cool. Humid as heck.

  15. PaulB/Eugene says:

    Took a peek at 00Z ECMWF: 90+ temps in PDX for all 10 days it looks….ULL approaches coast but then moves back W, heights build back in….T storms never make it to PDX on this model run it…neither does the marine air…

  16. Tetra says:

    😮 The real heat ridge isn’t even here yet according to the rest of the bloggers here!!

  17. Tetra says:

    OMG It’s like 77F outside at midnight!!!!!!!!!! What is this Sacramento Valley?

    You’d think this is Redding!

  18. Rob "Wrath" S.E. Portland says:

    This is ridiculous!
    Midnight 75.5F DP 64….
    It is going to be very oppressive the entire week.

  19. MtAngelMary says:

    Today’s high 95, currently 79, humidity at 58%. I believe I am fortunate to have a/c this year. It’s going to be a misrerable week…

  20. Rob "Wrath" S.E. Portland says:

    PaulB, I really appreciate your analysis. Excellent posts as usual…. Exciting times ahead I believe, and perhaps recording breaking with either high temps, or duration of 90+ temps.

  21. Still 75° out…Looks like the AC will be going all night…probably 24/7 all week……….

    75.0F Td 65.3 RH 72%

  22. PaulB/Eugene says:

    After looking at extended MM5…2-4 inches of convective precipitation expected in areas of SW Oregon…NW California….so maybe storms won’t be so dry…I doubt there will be that much precip though…

  23. Christiana--Forest Grove says:

    74 with humidity at 67% at 11:30pm

  24. PaulB/Eugene says:

    Looking at GFS, NOGAPS, Canadian models…trend seems to be to keep the upper low off the NoCal coast…which will keep us in a hot air mass for a long time…it is clearly warmer tonight than last night…which should get most of us 4-6 degrees warmer tomorrow…Eugene will probably top out at 100F Monday, then 104 Tuesday, 105F Wednesday, 99F Wednesday, 94F Thursday, 91F Friday. Disturbing trend in models is for the ULL low to then weaken or move W, allowing 500mb heights to get back to around 590-592 early next week. In 1977 there were a few days of 100+ temps, cooled off back into 90s, before going back up to 100+ for a day or so several days into the spell.
    I am thankful I do not live in the heat island of PDX….even if it got to 108F all time high, it would still likely be in low to mid 60s at dawn.
    As for T storms…ULL looks to be in optimal location late this week. I would be expecting high based storms with lots of lightning, not all that much precip. The firefighters are going to have a busy August I am afraid.

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