KIRO 7’s Pinpoint Meteorologists are calling for Pinpoint Alert Days for Sunday and Monday as the temperatures heat up around Puget Sound.
The sun is here and today will be gorgeous — in the 60s at the coast and 70s elsewhere. The reason today won’t be that much warmer than Thursday is due to the persistent onshore (or west-to-east) wind flow bringing in cooler air off the Pacific.
However, the cooling offshore breezes from the Pacific will be replaced by hot and dry offshore (easterly) wind flow by Sunday and Monday. This creates a bit of a “hairdryer effect” as the air descends out of the Cascade passes, warms, and dries naturally. It’ll also be breezy near the foothills. This will bring some of the hottest temperatures of the year so far to the whole area, and some daily temperature records will be broken on Sunday and Monday.
A Heat Advisory has been issued for most of Western Washington for Sunday and Monday.
I’m forecasting 88° for Seattle on Sunday, which would break the daily record of 86° from 1988, and on Sunday, the high in Seattle should hit 90°, breaking the old daily record of 88° from 1963.
It will be even hotter on Sunday and Monday near the Cascades (closer to that “hairdryer” of easterly downsloping winds) and south of Puget Sound. Expect more low 90s in these locations, including Chehalis, Olympia, Enumclaw, North Bend, and Monroe on Sunday, and some mid to even upper 90s on Monday! Some low 100s are expected down in the Willamette Valley of Oregon.
The heat will coincide with the first local World Cup match in Seattle on Monday, so those heading to the match or festivities should make sure to stay hydrated and find a source of air conditioning if overwhelmed by heat. Also, the UV index will be in the “very high” category, so sunblock is a must.
East of the Cascades, we’ll see more 90s through this period too, with some low 100s on Tuesday, as the heat breaks west of the Cascades
So how unusual is it to get to 90° in Seattle by the middle of June? Well, looking at the record book at SEA Airport, which goes back to 1945, it’s really not as unusual as you might think! While the average date to get to 90° for the first time is July 3, Seattle has notched a 90° day before the middle of June about 22% of the years of record, meaning it has happened about a quarter of the time.
It’s also worth noting that while we had healthy rainfall earlier this week, grasses and fine fuels will dry or “cure” very fast again once we get into the weekend heat, so try to prevent anything that could spark a grass fire or wildfire.