Click on a day for an hourly weather forecast
The temperatures in Sonoma in September are comfortable with low of 13°C and and high up to 28°C.
There is little to no rain in Sonoma during September, so it’s a lot easier to explore the city. Just remember to dress in warm layers, as it can still get pretty chilly.
Our weather forecast can give you a great sense of what weather to expect in Sonoma in September 2025.
If you’re planning to visit Sonoma in the near future, we highly recommend that you review the 14 day weather forecast for Sonoma before you arrive.
Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
---|---|---|---|---|---|---|---|
January | 14° / 5° | 6 | 25 | 0 | 130 mm | Good | Sonoma in January |
February | 15° / 5° | 6 | 22 | 0 | 120 mm | Good | Sonoma in February |
March | 16° / 6° | 7 | 24 | 0 | 117 mm | Ok | Sonoma in March |
April | 20° / 8° | 3 | 27 | 0 | 34 mm | Good | Sonoma in April |
May | 23° / 9° | 2 | 29 | 0 | 17 mm | Perfect | Sonoma in May |
June | 26° / 12° | 1 | 29 | 0 | 6 mm | Perfect | Sonoma in June |
July | 28° / 13° | 0 | 31 | 0 | 1 mm | Perfect | Sonoma in July |
August | 28° / 13° | 0 | 31 | 0 | 0 mm | Perfect | Sonoma in August |
September | 28° / 13° | 0 | 30 | 0 | 4 mm | Perfect | Sonoma in September |
October | 24° / 12° | 2 | 29 | 0 | 45 mm | Perfect | Sonoma in October |
November | 17° / 8° | 4 | 26 | 0 | 67 mm | Good | Sonoma in November |
December | 13° / 5° | 7 | 24 | 0 | 128 mm | Bad | Sonoma in December |