Weather in Seattle in September
September in Seattle is mild enough that walking is the default. This is a city-break month more than a sea-holiday month.
In United States, this is how Seattle actually wears September, not how a country centroid would. Compared with August and December, September sits in the middle of Seattle's year.
- Average temp
- 17°C
12–22°C
- Rainfall
- 41 mm
Not much rain
- Sunshine
- —
- Wind
- 11 km/h
What to expect
Daytime
Mild afternoons in Seattle are the prize in September. You can eat outside on the good days. You still want something for the breeze.
This is walking weather. Shade is useful, not essential the way it is in the hot months. A long outdoor day is a reasonable plan.
Rain
Mixed skies in Seattle in September. Dry days and wet days share the month. Outdoor plans need a backup, not a cancellation policy.
Pack a shell you will actually carry. The monthly table is the place for totals. This is the feel: usable, interrupted.
Evening
Evenings are cooler. A layer helps after sunset.
What to pack
A layer for cooler evenings
Where to stay in Seattle
Dates are a starting point for September.
Travel guides for Seattle
What to read before you book.
Average weather in Seattle
TemperatureRainfall
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FAQs about Seattle
Climate averages for Seattle, 1991–2020.
The best time to visit Seattle is between May and October, the most comfortable stretch of the year on these averages.
August is the hottest month, with an average around 19°C.
November is the wettest month, with about 160 mm of rain.
No. These are 1991–2020 climate normals from Meteostat, not a live forecast. Actual weather in any given week can differ.
