Pacific Northwest summers are generally boring from a weather geek’s perspective.  Apart from the occasional thunderstorm or extreme heatwave, there’s very little activity going on…other than temperature fluctuations caused by varying degrees of marine influence in the western valleys.  So I haven’t felt the need to post recently.  On a personal note…I did make it back to Central Oregon last week for the first time since November; it definitely feels like my “home away from home.”  Lots of sunshine & dry air without the suffocating heat and stuffy warm nights found in places like The Dalles, Pendleton and the Tri-Cities.

Back in May and June, many weather enthusiasts on various social media groups were predicting a mild summer this year, after the historic heat of the last 2 seasons.  By that, we generally mean lots of partly cloudy days in the western valleys, with a lot of days in the 70s & low 80s and not too many 90s.  Even inland locations like the Columbia Gorge & Columbia Basin can get some relief in a pattern like this, with fewer days 100+.  But now, as of July 21, I think it’s safe to say that’s not what happened.  So far, it’s been another extremely warm summer for most places west of the Cascades – albeit with a couple minor caveats.

Let’s delve into the data, for PDX only.  First, it was a pretty warm June this year, the 8th warmest on record to be precise:

A little drier than normal, and 2.2 F warmer on average.  That may not sound wildly warm, but remember that the “new” normals for 1991-2020 are significantly warmer than previous decades.  June 2023 was the 8th warmest on record, and most of that warmth was due to above-normal daytime temps, not so much the nights.  There were a lot more sunny days than a typical June, with no prolonged period of gloom.  Just a few wet days in the middle of the month, then right back to sunny & warm.

Here is the running average for July 1-20:

Much more dramatic!  4.6 degrees above normal so far, with a mean temperature of 74.0.  That would make this July tied for the 2nd warmest on record, and only 0.1 degree behind the warmest July (1985).  Of course the month isn’t over yet, and there are signs that the running average may drop slightly in the coming few days.  But it’s pretty remarkable nonetheless.  So far this season we have had a total of 13 days 90+, though 5 of those days were in May (a new record).  That means we have just about hit the normal “quota” of 90s, and we’re only about halfway through the season!

Now for some notes:

1.  We haven’t had any “extreme” heatwaves yet this season, and none are expected through the end of July.  And we haven’t hit 100 degrees yet.  Both of the last 2 summers saw a total of 5 triple-digit days at PDX.  Also, there haven’t been any oppressively warm nights (let’s say 68+) this year.
2. Other parts of the country have fared far worse.  Especially Arizona and Texas….can you imagine more than three weeks in a row with high temps in the 110s and low temps in the 90s?!?  That’s what Phoenix has had to put up with.  The PNW has been right on the edge of this extreme heat dome.  Had the heat swung further north at any time this month, we would have seen several more days 90+ and probably a few 100+ days, and our running averages would be even further above normal.
3. Why are we running so warm this month?  Basically it’s been very consistently “warmish-hot” the past 3-4 weeks, with most days in the mid 80s – mid 90s and very few days in the 70s.  A lot of medium-hot days generally beats a few extreme hot days, when it comes down to the final numbers.  Nights have also been quite warm overall, even if there are no extreme instances.

Looking ahead….we have two more relatively warm days this weekend for the western valleys, in the mid/upper 80s again.  Then Monday-Tuesday a weak trough swings by to our immediate north.  This brings in cooler onshore flow for a couple days, more clouds, and even a chance for a few sprinkles.  But most of the substantial rain will stay to our north, over the Olympic Peninsula, NW Washington and Vancouver Island.  Here is the ECMWF rain total through Wednesday morning:

It’s quite common for these summer systems to graze by to the north, delivering rain just a couple hundred miles away while SW Washington and western Oregon remain mostly dry.   In any case, the region turns dry again later next week for a few days, with temps near normal (low/mid 80s for us).

If you’ve been hoping that things might take a cooler turn as we head toward August, I have a little bit of bad news.  The CPC monthly outlook just came out for August, and we’re in the bull’s eye for more hot weather:

If this comes to pass, Summer 2023 will go down as the 3rd consecutive hot one, and the 7th anomalously warm summer in a 10-year period.  While it’s not unheard of to have three anomalously cool/warm seasons in a row, the trend the past 10 years is very unusual.  In fact, our summer temperatures have been hotter than what you might expect from global warming alone…but that’s a discussion for another time.

In any case, stay cool for the remainder of the season.  We should definitely have at least a little relief from the persistent warmth early next week.

Karl