Month-by-month travel weather
Seattle September weather
Seattle, United States · September
Layers become more useful as the month goes on
Early September can still feel like summer—bright and mild—while later in the month temperatures trend cooler.
Rain isn’t gone entirely, so a light rain option can keep plans flexible.
September averages at a glance
Average low
around 10–12°C
Average high
around 20–23°C
Average precipitation
around 35–60 mm
Rainy days
about 6–10 days
What to wear in September in Seattle
Actual feel will change with wind and rain, but use the suggestions below to build a comfortable layered outfit.
- • Light clothing by day + thin layer for evenings.
- • Optional sun protection on bright days.
- • Optional light rain layer.
Travel tips for visiting Seattle in September
- • If you walk late, a layer makes comfort more consistent.
- • You may start to feel the ‘rain season approaching’ vibe.
September weather in Seattle — FAQ
Q. Does rain increase in September?
A. The bigger shift often starts in October, but September can still have rainy days.
Q. Is September a good time to visit?
A. Often yes—just plan for cooler evenings later in the month.
Explore Seattle
These pages are connected so you can compare conditions and decide for yourself.