September · United States
Best time to visit Seattle in September Weather, crowds & prices
Weather in Seattle in September
Average temperature 16°C, 47 mm of rain, about 13 days with 6+ hours of sunshine and 80% humidity — based on the five most recent complete years of ERA5 data (2021–2025).
September score
8.4/10
Ranked #4 of 12 months
- Avg temp
- 16°C
- Rainfall
- 47 mm
- Humidity
- 80%
- Days with 6h+ sun
- 13
- Crowd Density
- Moderate Crowds
- Average Expenses
- $$ · Moderate Cost ($$)
September in Seattle scores 8.4/10 for sightseeing and cultural travel - an above-average month (#4 of 12). Expect around 16°C, 47 mm of rain, and roughly 13 days with 6+ hours of sunshine this month.
Ferry views, coffee culture, and evergreen trails peak in clearer May-September weather.
September in Seattle: strong conditions, 4th of 12
September averages 16°C (60°F), the range most people find easiest for walking a city all day without either overheating or losing daylight to weather.
Rainfall runs 47 mm, so plan one flexible day in three; you still get about 13 days with 6+ hours of sunshine and 12.3 hours of daylight.
It scores 8.4/10 here, 4th of 12 months, against 9.6/10 in the destination's best month.
Pack layers you can shed by midday plus one warm layer for the evening, a packable rain layer.
Figure on mid-season pricing, with crowds are moderate.
Frequently asked
- What is the weather like in Seattle in September?
- In September, Seattle averages 16°C, 47 mm of rain, and about 13 days with 6+ hours of sunshine. Its climate-comfort score is 8.4/10.
- Is September a good time to visit Seattle?
- September earns a 8.4/10 climate-comfort score. Use the year-round chart to weigh the weather against your budget and crowd preferences.
- How much does it rain in Seattle in September?
- Expect about 47 mm of rain in September. Average humidity is 80% and there are about 13 days with 6+ hours of sunshine.
Curated in Seattle
Tickets & experiences
Things to do in Seattle
Seattle, United States. Live activities and tours from GetYourGuide, matched to this destination.