Friday Harbor weather in September 2025

Expect 18°C daytime maximum temperatures in the shade with on average 7 hours of sunshine per day in Friday Harbor in September. Check more long-term weather averages for Friday Harbor in September before you book your next holiday to Washington State in 2025/2026.

• 18
  18°C max day temperature
• 7
  7 hours of sunshine per day
• 9
  9 days with some rainfall
• 10
  10°C min night temperature
• 13
  13 hours of daylight per day
• 0
  No heat & humidity
• 36
  36 mm of monthly rainfall
• 5
  5 (Moderate) UV index
• 12
  12°C sea temperature

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The September weather guide for Washington State (Friday Harbor) 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 / mm)  |  Imperial (°F / inches)

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Friday Harbor September sunrise & sunset times

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

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