Santa Rosa Weather in September

What's the weather like in Santa Rosa (California) in September 2025?

The climate in Santa Rosa during September can be summarized as warm and dry.

September is in the fall / autumn in Santa Rosa and is typically the 3rd warmest month of the year. Daytime maximum temperatures average around a comfortable 27°C (81°F), whilst at night 10°C (51°F) is normal.

Santa Rosa weather averages (imperial / metric)
Daytime temperature 27°C 80.6°F
Nightly temperature 10.4°C 50.7°F
Average temperature 18.7°C 65.7°F
Daily sunshine 10.2 hrs
Avg rainfall 12 mm 0.5 ins
Rainy days 2 days
Sea temperature 14.4°C 57.9°F
Humidity 68%
Windspeed 15.1kph 9 mph

On average September is the 4th driest month of the year in Santa Rosa with around 12mm 0.5 inches of rain making it a dry time to visit. This rainfall is typically spread over 2 days, although this may vary considerably.

On the flip side this corresponds to an average of 10.2 hours of sunshine per day.

September temperatures in Santa Rosa

Santa Rosa average temperature in September

September rainfall

Santa Rosa average rain in September

September hourly sunshine

Santa Rosa 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 Santa Rosa 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

Santa Rosa weather stats

Santa Rosa weather statistics
Hottest month: July 27.2°C 81°F
Driest month: July 2mm 0.1ins
Sunniest month: April 11hrs
Coldest month: January 13.4°C 56.1°F
Wettest month: January 182mm 7.2ins
Map showing location of Santa Rosa (38.44047, -122.71443) Santa Rosa map pin © Google

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