Weather Blog

Seattle nearly sets new mark for temperature whiplash

Seattle nearly sets new mark for temperature whiplash
Mt. Baker peeks out behind I-90 on a sunny day in Seattle on July 1, 2014.

Talk about flash in the pan...

Seattle's 94-degree "heat wave" lasted all of 24 hours this week, as a thermal trough quickly built up then was shoved east of the Cascades before it even had a chance to buy a postcard.

I was actually quite surprised that Seattle reached 94 after only reaching 78 degrees the day before. Usually Seattle needs a better springboard the day before to reach into the 90s the following day, although there are a handful of dates it reached 90+ while being in the 70s before.

And Seattle is quite notorious for having heat waves end with a major crash in temperatures when a strong marine push comes in -- dropping from the 90s to 70s -- or even 60s -- is not uncommon either.

But it seemed strange to me to go from 78 all the way up to 94, then back down into the upper 70s and low 80s over the course of 72 hours. We get one or the other, but usually the main heat event lasts a little while longer on either side.

Sure enough, my suspicions were confirmed -- it's rare. There's only a handful of times we've made such a dramatic rise then drop. Wednesday, we were oh-so-close to making it the first time in Sea-Tac history (since 1945) that Seattle had a 90+ degree day without reaching at least 80 degrees either the day before or after. But then Sea-Tac went and hit 81 at the buzzer Wednesday and totally took all the wind out of the sails of this blog.

But since I had already written it and done the research, here we are, with a few edits to the original post and ceding a coveted spot on the KOMONews.com home page since...we didn't really break any never-before-seen/all-time records. But I'm not bitter, Sea-Tac thermometer. (OK, maybe a little :) )

Other times of similar events were in 1981, we went 79, 94, 80 on Sept. 6-8. Also just last year we reached 80 on Sept. 10, then 93 on Sept. 11 and then cooled to 78 on Sept. 12. That's a bit easier to do in September because we're in the cooling down process, but for the first of July? Much higher degree of difficulty (no pun intended.)

Likely the largest case of "temperature whiplash" came in 1991 when it was 82 on July 22nd, then it zoomed all the way up to 99 degrees on July 23rd -- at the time, tied for the all-time Seattle high temperature record -- only to have it cool back to 70 the next day (see! Big marine push.) I haven't crunched those numbers but I'll bet 29 degrees is probably up there, if not the record for greatest single day cool down.