What September feels like in Seattle
September is early autumn in Seattle. Daytime temperatures are mild — neither cold nor hot for walking around. Evenings bring a clear drop in temperature, and nights are cool. Moist air is typical, yet it seldom feels heavy at this time of year.
Rain in Seattle in September
It is a changeable month: rain comes about one day in 3, with dry spells in between. A rainy day brings about 7.3 mm (0.3 in) on average — steady rain rather than a passing shower. That is close to Seattle's typical rain per wet day for the whole year (about 8.3 mm).
Daylight and sunshine in September
On 15 September the sun rises at about 6:45 am and sets around 7:24 pm local time, giving 12 h 39 min of daylight. Evenings are drawing in — 1 h 41 min less daylight than mid-August. The sun is out for roughly 76% of those daylight hours, so there are plenty of bright spells.
How September compares to the rest of the year
September is the 3rd warmest month of the year in Seattle. Afternoons run 3.7°C (6.7°F) cooler than in August, with 37 mm more rain. Temperatures keep falling into October. The next month's average high: 14.7°C (58.5°F).
Who September suits
- Sightseeing: a good fit — the weather rarely gets in the way of a city walk.
- Parks & outdoor: a good fit — comfortable for long walks and picnics.
- Beach: less ideal — too many rainy days.
- Hiking: a good fit — mild temperatures for trails.
Tips for visiting Seattle in September
Versatile Layers
Days are noticeably warmer than nights — layers you can add or remove.
Rain Protection
A compact umbrella and a light waterproof jacket.
Sunglasses
Plenty of sun, so bring sunglasses and a cap.
Quick questions
How warm is Seattle in September?
Afternoons average 20.6°C (69.1°F) and nights about 12.2°C (54°F) — mild by most people's standards. It is the 3rd warmest month of the year.
Does it rain a lot in Seattle in September?
Quite a lot — 66 mm spread over about 9 days.
What should I wear in Seattle in September?
Pack versatile layers, rain protection and sunglasses. Add a layer for after dark.
Is September or October better for visiting Seattle?
September, clearly: it ranks #4 of 12 among Seattle's months, against #7 for the other. October is cooler and has more rainy days.