September is off to a pretty cool start in Western Washington — in fact, it’s the coolest start to September Seattle has seen in 16 years.
The average temperature through the first two weeks of the month is just 61.8 degrees, which is 2.7 degrees below normal. You have to go back to 2010 to find a cooler start to September, when the average was 61.0 degrees.
We’ll add a little rain to the mix this morning as a weak upper-level wave moves across the area. Expect widespread clouds with a few pockets of light showers. They’ll be spotty enough that almost anywhere could see one, but we’re not expecting much rainfall. Most spots will pick up just a few hundredths of an inch, with a few locations seeing more than a tenth. The showers should be mostly done by midday, with increasing sunbreaks this afternoon. Temperatures will stay a bit below normal, topping out in the upper 60s.
Then things turn warmer.
High pressure builds in tomorrow, and a little offshore flow will help temperatures jump into the mid-70s. We’ll start Wednesday and Thursday with some patchy fog and cooler temperatures, followed by plenty of sunshine in the afternoon.
The wind turns back onshore later Thursday into Friday, bringing some morning clouds Friday and each day this weekend. But those clouds should give way to afternoon sunshine, with highs right around 70 degrees.
So, after a cool start, we’re looking at a pretty nice finish to the week and weekend.
©2026 Cox Media Group
