Scott Sistek 
ECMWF 500 mb heights map for Sunday showing large ridge of high pressure parked over the entire Western U.S.
Happy official start to Seattle’s rainy season!
(cricket…cricket…)
October 1 is the date on the calendar that we “reset” the water year for tracking annual rainfall and generally speaking, the start of those “8 months it rains out of the year in Seattle.”
But a glance at the long range forecast shows anything but! Rub your eyes all you want, but that is a bona fide 7 days of sunshine on the forecast map matching up with 7 dates on the October calendar.
It’s all part of a sprawling ridge of high pressure that is going to consume much of the West Coast for the next while — a very summer-like pattern anchoring itself here in early autumn.
For much of the West, the weather pattern is threatening heat records. Parts of the San Francisco Bay Area are in the 90s to near 100. And with a boost from Santa Ana winds, Southern California is looking at potential 100-plus degree temperatures — Los Angeles is expecting to hit 102 on Saturday.
Even Portland this weekend is pushing the mid 80s, which would be record heat for them too.
For Seattle and Western Washington though, we are on the outer fringes of the heat, and instead will be comfortably warm — highs around Seattle this weekend will top out in the upper 60s to low 70s with Sunday looking like the warmer day as we get a little east wind boost. But Seattle’s record high is 76 on Sunday and that still looks safe.
You know what else looks safe? ANY and all outdoor plans. Hiking, walking that dog, going for a jog, getting in that rare visit to the pumpkin patch that ISN’T muddy. Actually this could be one of the best pumpkin patch visit days ever, with only demerits for being kinda warm that it won’t feel crisp to grab a hot cider or hot chocolate yet, but you could just go early or late.
We’ll even bring back the light onshore breezes Sunday night and the rest of next week is looking flat out comfortable with some patchy morning fog but plenty of sun with seasonal highs in the 60s. Our next even little bit of rain so far doesn’t show up on the charts until maybe October 9 or 10.
IS THIS ‘GUILT FREE’ SUNSHINE THOUGH?
I have been thinking about that. Is enjoying a week of sun in early October like eating 6 chocolate doughnuts for breakfast and feeling great about it then…and then not-so-great about that choice later? (This is TOTALLY not me coming up with this metaphor from reminiscing about any personal experience from my college days. Nope.)
(That might have had two maple bars mixed in…)
I’d say for EARLY October… we’re OK. While the rainy season officially kicks off, the REALLY rainy season doesn’t get going until about the third week of October.
Dana Felton with the Seattle office of the National Weather Service says going the first week of October dry has happened 14 times in the past 81 years at Sea-Tac… or roughly about every six years. The last time we did that was 2022…and 2020. Thanks, math!
But I know what you’re thinking: “Scott, why didn’t you just stop at 2 doughnuts… or maybe 3 at the absolute maximum?” No? Or is it: “But what about Super Mega Thanos El Niño?”
That is the wild card this year. One week of sunshine in early October? Fine. Eat those doughnuts. Four weeks of sunshine in October? Distressing. 12 weeks of sunshine in Seattle’s winter? Problematic.
Right now the long range outlooks are very much leaning that all of October will end up on the dry side.
That doesn’t mean it’ll be sunny or dry for all 31 days; just that the rainy season may not be so rainy to start this time.
As I’m sure you’ve heard, most of the dire El Niño predictions for the Pacific Northwest center around a much warmer and somewhat drier winter. October isn’t usually a big mountain snow producer, so a warm and dry October is manageable. But if I have to keep repeating this sunny forecast over the next few weeks: :/
But for now, I’d say it’s fine to enjoy the sunshine this week; and then be OK if that rain out in the far long range comes to fruition (which, of course may be on a weekend so pumpkin patch may be back to traditionally muddy).
But if you do go to the pumpkin patch, just go light on those doughnuts.