Friday Harbor Weather in September

What's the weather like in Friday Harbor (Washington) in September 2025?

The climate in Friday Harbor during September can be summarized as mild and reasonably dry.

September is in the fall / autumn in Friday Harbor and is typically the 4th warmest month of the year. Daytime maximum temperatures average around 18°C (65°F), whilst at night 10°C (49°F) is normal.

Friday Harbor weather averages (imperial / metric)
Daytime temperature 18.2°C 64.8°F
Nightly temperature 9.6°C 49.3°F
Average temperature 13.9°C 57°F
Daily sunshine 7.2 hrs
Avg rainfall 36 mm 1.4 ins
Rainy days 9 days
Sea temperature 13°C 55.4°F
Humidity 79%
Windspeed 10.8kph 7 mph

On average September is the 5th driest month of the year in Friday Harbor with around 36mm 1.4 inches of rain making it a reasonably dry time to visit. This rainfall is typically spread over 9 days, although this may vary considerably.

On the flip side this corresponds to an average of 7.2 hours of sunshine per day.

September temperatures in Friday Harbor

Friday Harbor average temperature in September

September rainfall

Friday Harbor average rain in September

September hourly sunshine

Friday Harbor average rain in September

The data used in these monthly averages covers a period of over 100 years right up until last year. As such they are a valid prediction of what to expect for the weather in Friday Harbor in September 2025.

Other monthly averages

Best places to visit in September

UV index Best time to go?

Beta

Current (hourly) weather 15 day forecast

Friday Harbor weather stats

Friday Harbor weather statistics
Hottest month: August 20.6°C 69.1°F
Driest month: July 20mm 0.8ins
Sunniest month: July 10.7hrs
Coldest month: January 6.6°C 43.9°F
Wettest month: December 113mm 4.4ins
Map showing location of Friday Harbor (48.53427, -123.01712) Friday Harbor map pin © Google

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