What’s Going On? Warmest May In Portland & Record Dry Late Spring

6pm Memorial Day

For the 4th consecutive year we’ve seen a DRY Memorial Day Weekend.  Hard to believe!  But it fits the weather regime we’ve seen for the past 6 weeks…Unusually dry and warm.

We’ve seen a week or two of unusually warm and dry weather in springtime, but this is getting strange.  Folks, we’re living through an unprecedented period of warm and dry weather…one that hasn’t been seen this time of year for at least 80 years, or much longer.

As of today we are experiencing the warmest May on record here in Portland, and in some other spots.  We haven’t seen a single below-average day…just 3 right at average so far…

Mark Monthly Climate Calendar 1


If we add in the next 3 days from our 7 Day forecast, it becomes a tie for #1 with 1992.

Even stranger is the lack of rain.  The past 6 weeks we’ve seen no soaking rain!  The .34″ we’ve seen in the entire 2nd half of meteorological spring (ends Thursday) is less than half of the previous dry record! 


and we’re in the 2nd longest dry streak we’ve ever seen in May…


I’ve lived west of the Cascades all except maybe 2 years of my life.  Never have I seen it so dry in late May.  My yard/garden/gravel driveway looks just like July…dry and dusty.  In past years when we do get a dry spell in May, we always see a soaking on the maps/models within the next 7-10 days.

Why has it been so dry and warm?  It doesn’t look all that impressive on a weather map, but here’s the 500 millibar height anomaly for the past month.


The cool colors are lower than average heights (generally colder than average).  The opposite end of the spectrum are the yellow/orange areas.  You see over SW Canada and NW USA heights have been well above average.   Now it’s typical for upper-level heights to gradually rise from April through August.  But the net effect of that positive anomaly is to push our season “forward” a month or so with heights more like what we would typically see in June or early July.  And in early summer those higher heights typically push weather systems farther north and dry/warm us out/up.

Do we see a soaking ahead?  Likely not a soaking, but there does appear to be an increased chance for a least some dust-settling showers about a week from now.  Check out the ECMWF ensemble 24-hour rain forecast.  Note that any colored horizontal bar says at least .10″ in a 24 hour period.  You don’t see many of those bars do you?  The best chance for showers seems to be right around the 3rd-5th (Sunday-Tuesday), but even that is only appearing on maybe 1/2 of the ensembles.

KPDX_2018052812_eps24_precip_360 (1)

Temperatures WILL be cooler this next week as weak upper-level troughing hangs nearby.  Maybe most noticeable will be cooler temperatures at night due to the dry airmass arriving tonight.  At least that drier/cool airmass helps to break up the marine low clouds so we’ll see plenty of sun the rest of the week…mixed with clouds.  A pleasant end to a crazy warm/dry May!

Chief Meteorologist Mark Nelsen

38 Responses to What’s Going On? Warmest May In Portland & Record Dry Late Spring

  1. runrain says:

    An example how bad these long range forecasts are: 14 days out the Weather Channel forecast 86 deg for parade day. That forecast high is now 59 deg!

  2. Roland Derksen says:

    Cloudy, cool breezy conditions through this first week of June 2018. But, I kind of like it: You can do a lot of things outside because it’s dry. I recall June 5, 2008. Quite a diffferent story that day: Overcast with steady light rain here, and a high of only 52F.

  3. Paul D says:

    Saturday shows “showers and breezy”. Is it going to be more than feeling like someone spitting on us?

  4. K says:

    A little dampening (or more) possible for the metro area according to (at least) the GFS around the 9th. Unfortunately (or fortunately) I’ll be missing it, as I will be in another country by then.

  5. Roland Derksen says:

    We were supposed to get a pretty good amount of rain yesterday here (0.5-1inch) but hardly anything resulted.(trace). Have to hope we get something close to average this month.

  6. W7ENK says:

    Finally got a few drops of free sky water in my garden last evening, though that was after I sprayed a bunch of the expensive municipal water in there. I’ll take what I can get.

  7. K says:

    TBH this is one of the most boring weather months I can remember.

  8. Roland Derksen says:

    My warmest and driest May is over, and now with the start of June we have a chance of showers.I don’t expect much tonight, and I doubt it will be a lot on Sunday. I have tomato fruits on my bushes already: I’ve never seen them so early!

  9. K says:

    Showers passing over the West Hills.

    • lurkyloo says:

      I’m currently getting a nice dose of free water!

    • Ken in Wood Village says:

      I was driving from Ridgefield, WE when I hit a heavy shower. It was scary because there was so much oil coming up from the road that I thought either I or someone else would spin out. By the time I got home, it was hardly raining. It did rain a lot between 8 and 9pm. 🤗

  10. Paul D says:

    Got a bit of rain around 7:30am in Hillsboro. Is that it?

  11. W7ENK says:

    Still waiting for free water to fall on my garden. I even took a chance last night and left all my lawn furniture out, my BBQ/smoker wide open and my car windows open a skosh in hopes that maybe the Universe would take advantage of such a glaring opportunity, but nope.

    I guess I’ll have to drive down to Kaiser with a few jugs?

  12. Ken in Wood Village says:

    I was just looking around the world and noticed some areas in Antarctica are running -90F. I also see a few Low’s with pressures from 950’s to 970’s. Seems the Southern Hemisphere gets more of the action 😦

    • W7ENK says:

      It’s Wintertime down there, today is the equivalent of our December 1st in the Southern Hemisphere. Just like up here during our Winters, their weather is more active right now.

      • Ken in Wood Village says:

        I knew it was winter down there. I just wish our (the NW) winter was more active like theirs. I did get a little rain here. Not much but it was nice 😉

  13. W7ENK says:

    This probably isn’t good…

  14. W7ENK says:

    Woke up to 42 degrees this morning. Went to bed with all my windows open, which made getting out from under my blankets a challenge. Kind of pushing it with the pepper plants too, they don’t react well to temperatures below 50. Hoping they didn’t suffer any damage!

  15. Roland Derksen says:

    It somewhat surprises me that May 2016 is ranked no.4 on the list, and May 2015 isn’t there at all. Anyway, coolish morning here as well:48 F. for the minimum.

  16. Paul D says:

    42 at my house this morning! Hasn’t been that low in a long time. And my house is down to 68! It’s going to be a nice day!

  17. Ken in Wood Village says:

    Ok, that worries me. I heard about a flare up from the Eagle Creek fire. I really hope that was just it and nothing else will flare up but I’m worried if another flared up when we have strong East winds. That would be nuts and we could start all over again what happen last year. Not good, we need some rain and soon.

    • Anonymous says:

      That’s so crazy how fire could “hibernate” for the winter. Rather scary.

      • Ken in Wood Village says:

        I know what you mean. I wasn’t as close to the fire like other people but I was close enough to be scared by it. I don’t want to experience what I went through 6 to 7 months ago. I just hope the fire won’t flare up again.

  18. W7ENK says:

    A little disappointed I didn’t get some free water for my garden over the weekend, but that’s okay, there’s still plenty of the kind I pay for yet…

  19. Lynn G. Hocker says:

    This is very very very upsetting. People
    deny global warming exists but it obviously
    does. Even if everyone wants to argue about
    what’s causing it — it’s happening and
    it’s frightening! California is going to end
    up with the climate of Mexico, and Oregon
    is going to be like Southern California!

    I happen to LOVE the rain!!! I always have!
    I don’t want to live in a world getting hotter
    and hotter, and dryer and dryer! Scientists
    warned us about this way back in 1970!!!
    In my naivety I thought we’d do something
    about it. Never in my wildest dreams did
    I think we would just ignore it and let things
    get worse and worse. 😦

    Thanks for your report, Mark


    • Roland Derksen says:

      I thought scientists were worried about global cooling back in the 70’s? At least the ones I read about…

      • W7ENK says:

        They were. I specifically remember hearing from my parents that scientists were heralding the impending “ice age” all throughout the 70s. “Global Warming” didn’t really become a thing until Al and his “hockey stick” graph went mainstream in the late 90s.

        But since this topic is taboo on Mark’s blog, I’ll digress.

  20. cgavic says:

    summer! finally!

  21. Paul D says:

    This scares me. What is summer going to be like? Unprecedented heat and dry? I sure hope not.

    • Roland Derksen says:

      Not necessarily. Recalling spring 1982, I can remember it was hot through June, then July and August were mainly cloudy and cool. (that was in my area, of course)

  22. K says:

    Ugh. I’m heading to India soon, so hopefully some exciting weather awaits me. I’ll continue to hop on and off the blog though. But I can’t help but look forward to next winter.

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