The climate in Santa Rosa during September can be summarized as mild and a little damp.
September is in the spring in Santa Rosa and is typically the 4th coldest month of the year. Daytime maximum temperatures average around 18°C (65°F), whilst at night 9°C (49°F) is normal.
Daytime temperature | 18.4°C 65°F |
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Nightly temperature | 9.3°C 48.7°F |
Average temperature | 13.8°C 56.8°F |
Daily sunshine | 6.7 hrs |
Avg rainfall | 97 mm 3.8 ins |
Rainy days | 9 days |
Sea temperature | 12.3°C 54.1°F |
Humidity | 75% |
Windspeed | 17.6kph 11 mph |
On average September is the 4th wettest month of the year in Santa Rosa with around 97mm 3.8 inches of rain making it a a little damp 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 6.7 hours of sunshine per day.
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.
Best places to visit in September
Hottest month: | January | 28.7°C 83.7°F |
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Driest month: | December | 82mm 3.2ins |
Sunniest month: | January | 9.9hrs |
Coldest month: | July | 15°C 59°F |
Wettest month: | October | 108mm 4.3ins |