SEATTLE -- Admit it, when Seattle had nearly 2 inches of rain last week as the echoes of Labor Day weekend were still wafting through the air, you were probably thinking our summer weather was done?
But summer's still got a few tricks up its sleeve in what is shaping up to be quite the swan song, with perhaps some of the hottest temperatures of the summer saved for the very end, especially for those of you outside the central Puget Sound region who have missed out on many of the very warm days the Emerald City has had so far.
A warming thermal trough is working its way up from the south -- already evidenced by temperatures in the 90s along the south Oregon coast. It will bring an increase in sunshine and temperatures as we head into the middle of the week -- likely breaking records as it does so -- with only modest cooling as we head into the weekend.
Highs around Seattle should climb into the mid 80s on Tuesday, and then upper 80s to perhaps low 90s on Wednesday and possibly into Thursday. Record highs for Seattle are 85 on Tuesday (1946), 87 on Wednesday (2009) and 85 on Thursday (1975). But while Seattle has had a 93 degree day already this summer and a baker's dozen of days 85 degrees or warmer, much of the rest of the region has had a relatively mild summer, especially north of Everett and along the coast, where persistent marine breezes that have been too weak to reach Seattle have kept it cooler there.
But this time, everyone will feel relatively toasty and this will be more of a traditional widespread summertime heat wave -- caused when east winds are drawn out to sea to meet the offshore trough. Those east winds not only hold back the cooling seabreeze but also warm a bit more when they sink down the western slopes of the Cascade and Olympic Mountains. (It's also a drying wind, so no worries about that muggy warmth we've persistently had this year.)
So for the likes of Bellingham, Port Townsend, Port Angeles, and Hoquiam, it's going to feel almost like summer's first blast of heat -- certainly the first blast of a few days' of heat. Hoquiam has had only one day over 80 and three others warmer than 76 -- a testament to the lack of east wind. This time around they have a chance to hit 80 degrees on back-to-back days Tuesday and Wednesday.
The trough will begin to move inland and weaken just a bit on Thursday, allowing the marine breezes to eventually cool off the coast and North Sound although the Puget Sound region and southwestern Washington will likely have another very warm day.
The east winds are gone on Friday and Saturday, allowing for some cooling in the interior, but so far, indications are the marine breezes will remain weak, keeping temperatures still above normal -- perhaps in the upper 70s to low 80s, or about on par what has been the common pattern of a warm interior but much cooler coast.
But long range models suggest a much larger cool down for early next week with potential for showers, and suggest that pattern will stick around for a while. By then, summer will be nearing its official end and with it, any real chances for seeing these kind of warm temperatures again until next year.
Seattle reaching into near record territory for number of 80-degree days
The upcoming heat wave is likely going to give Seattle at least 40 days of high temperatures at or above 80 degrees, moving into rare territory. The city was at 38 days as of Sunday, tied with 1985 for fifth-most in Seattle history and already ahead of 2009's very warm summer that had 36 days.
- 1 - 47 days: 1958
- 2 - 46 days: 1967
- 3 - 45 days: 1961
- 4 - 40 days: 1987
- 5 - 38 days: 2013
- 5 - 38 days: 1985