Avg High
Seattle in September
Verdict
In Seattle, September has a distinct autumn feel. As the season moves along, temperatures are dropping quickly. You can usually expect a mild month that feels manageable day to day. Breezes can be part of the character, especially in exposed spots.
It suits travellers who want straightforward weather for sightseeing and day trips. Lookouts and coastal walks can feel sharper when the wind is up.
Avg Low
Rain
Daylight
13h
What to expect
- Daytime feel - Comfortable days with evenings that feel distinctly cooler. Overall it feels close to what you’d expect.
- Rain pattern - Regular showers. Rain is usually intermittent rather than relentless. A rain layer is a smart default.
- Sun & UV - Sun is noticeable. You'll feel fine, but it's still easy to get caught out. Shade breaks feel genuinely worthwhile.
- Exposure - Often breezy, and gusts can catch you in exposed spots. A light outer layer helps when you’re in the shade.
September in context
How it compares to the rest of the year in Seattle.
Hottest (avg)
#3 / 12
Wettest (avg)
#9 / 12
Daylight Hours
#6 / 12
Windiest (avg)
#10 / 12
Highest UV
#6 / 12
Most Humid
#8 / 12
Temperature
- Daytime high
-
- Nighttime low
-
- Feels like (avg)
-
Sunshine
- Daylight
- 12.5 hours
- UV index (max)
- 6
- Typical sun hours
- 05:47 – 18:19
Rain & Snow
- Total
-
- Rainy days
- 11
- Cloud cover
- 52%
- Snowfall
-
Humidity & Wind
- Humidity (avg)
- 76%
- Wind (avg)
-
- Wind (max gusts)
-
Frequently asked questions
Is September a good time to visit Seattle?
Typical September days in Seattle reach highs of 20°C (68°F) with nights around 12°C (54°F). It usually feels mild by day and cool after dark. Overall, September sits in the middle of the Seattle climate range.
What are temperatures like in September?
Daytime temperatures in September typically peak near 20°C (68°F), while nights drop to around 12°C (54°F). Expect mild afternoons and cool evenings.
How much does it rain in September?
Rainfall in September averages 65 mm (2.6 in) across roughly 11 days. Overall it is a quite rainy time of year, so a light rain jacket and waterproof shoes are very handy.
How many hours of daylight are there in September?
You can expect about 13 hours of daylight in September. Sunrise is typically around 05:47 and sunset near 18:19. Daylight is fairly typical, with enough time for sightseeing.
How strong is the sun in September?
UV levels are moderate (around 6); sunscreen and sunglasses are still a good idea.
Is it windy in September?
In September, average wind speeds are around 8 km/h (5 mph), with gusts on the windiest days reaching about 43 km/h (27 mph). On the ground, it is it often feels breezy, especially in more exposed spots or along the coast.