Weather Blog

Seattle weather rates a 4...then a 5. But it's not your ordinary scale

Seattle weather rates a 4...then a 5. But it's not your ordinary scale
And to think, 10 days ago we were setting a record for most consecutive days under 65 degrees in June.  By Sunday, it might stay warmer than 65 from start to finish!

Our first true heat wave of the year is upon us (not counting the 90 degree day we had in May, which was one day and done) as temperatures are expected to soar to near-record levels.

High pressure is in command overall, and a weak thermal trough is developing from the south and will move into the area beginning Friday night hand hanging around through the weekend.   Highs will reach the mid-upper 80s for the greater Seattle area, but spots south and east might get into the 90s. The neat part about forecasting weather in the Puget Sound area in summertime is that it basically falls into six different patterns, which are all dependent on the prevailing winds.

1. If you have a strong westerly/marine breeze, we usually get stuck under morning clouds for most of the day (perhaps some drizzle) and highs in the mid-upper 60s.

2. If we have a moderate westerly marine breeze -- which is the most common day-to-day scenario around here -- that's our morning clouds, afternoon sunshine, with highs in the 69-76 range -- a tad warmer away from the water.

3. If we have a light marine breeze, that usually means just brief morning clouds, with sun in the afternoon, but a sea-breeze developing in the afternoon. That will usually cap our temperatures in the 76-82 degree range in Seattle -- depending on the strength of the sea breeze -- and there is a noticeable difference in temps near Puget Sound as opposed to inland areas (which can get into the mid 80s). Yet the Coast is still in the mid 60s.

4. If we have pretty much no breeze, it's a full sunny day, and temps will make it into the 80-86 degree range everywhere, but not so much a gradient between water and inland temps. Coast usually gets into the low-mid 70s.

5. If we have an easterly/offshore breeze, it's a full sunny day, and temps can range anywhere from 85 to 99, depending on how strong the breeze is (stronger the breeze, the hotter it gets.) Eastern foothill areas are usually 5-10 degrees warmer than Seattle, and it even gets into the 80s/90s on the Coast.

6. And then there's everything else, when we get rain systems and such which are their own weather beasts.

Western Washington is holding in the '3' pattern Friday, but we were working our way to a strong 4, or a moderate 5. The difference this time is the offshore wind is not expected to be strong and that's why temperatures are not expected to well into the 90s, but more the upper 80s/low 90s.