Seattle weather in September 2025

Expect daytime maximum temperatures of 70°F in Seattle, Washington State in September based on long-term weather averages. There are 7 hours of sunshine per day on average with typically 1.9 inches of rainfall in the month.

  • 70°F maximum daytime temperature in September in Seattle70
    70°F max day temperature
  • 7 hours of sunshine per day
  • 9 days with some rainfall in September in Seattle9
    9 days with some rainfall
  • 52°F minimum night-time temperature in September in Seattle52
    52°F min night temperature
  • 13 hours of daylight per day in September in Seattle13
    13 hours of daylight per day
  • No heat & humidity in September in Seattle0
    No heat & humidity
  • 1.9 inches monthly rainfall in September in Seattle1.9
    1.9 inches of monthly rainfall
  • UV (maximum) index 5 (Moderate) in September in Seattle5
    5 (Moderate) UV index

More about Seattle

Seattle by month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Recommended for Washington State

Aer Lingus: Top deals on flights to Ireland & beyond

  • Save on flights to Ireland, USA, Canada & Barbados
  • Book top flight deals online with Aer Lingus
  • Fly to Dublin, Belfast, New York, Orlando, LA & more
Go to Aer Lingus deal >>

View all Aer Lingus offers

The September weather guide for Washington State (Seattle) shows long term weather averages processed from data supplied by CRU (University of East Anglia), the Met Office & the Netherlands Meteorological Institute. Find out more about our data sources.

Metric (°C)  |  Imperial (°F)

Back to top

More about the USA

How hot is it in Seattle in September?

Daytime temperatures usually reach 70°F in Seattle in September, falling to 52°F at night.

How sunny is it in Seattle in September?

There are normally 7 hours of bright sunshine each day in Seattle in September - that's 57% of daylight hours.

Does it rain in Seattle in September?

There are usually 9 days with some rain in Seattle in September and the average monthly rainfall is 1.9 inches.

Seattle September sunrise & sunset times

Browse the sunrise and sunset times for Seattle in September 2025. Select a month to view Seattle sunrise and sunset times for the next 12 months.

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 05:28 18:49
Monday, 15th September 2025 05:47 18:21
Tuesday, 30th September 2025 06:08 17:50

Related posts

Popular travel offers

Explore holidays in the sun for less

More holidays

Airport parking

More parking

Airport lounges

More lounges

Top ^