Click on a day for an hourly weather forecast
The temperatures in Santa Rosa in September are comfortable with low of 13°C and and high up to 29°C.
There is little to no rain in Santa Rosa 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 Santa Rosa in September 2025.
If you’re planning to visit Santa Rosa in the near future, we highly recommend that you review the 14 day weather forecast for Santa Rosa before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | 14° / 5° | 5 | 26 | 0 | 152 mm | Good | Santa Rosa in January |
| February | 15° / 5° | 5 | 23 | 0 | 155 mm | Good | Santa Rosa in February |
| March | 17° / 6° | 7 | 24 | 0 | 133 mm | Ok | Santa Rosa in March |
| April | 20° / 7° | 3 | 27 | 0 | 44 mm | Good | Santa Rosa in April |
| May | 23° / 9° | 2 | 29 | 0 | 27 mm | Perfect | Santa Rosa in May |
| June | 27° / 12° | 1 | 29 | 0 | 9 mm | Perfect | Santa Rosa in June |
| July | 29° / 12° | 0 | 31 | 0 | 2 mm | Good | Santa Rosa in July |
| August | 29° / 13° | 0 | 31 | 0 | 2 mm | Good | Santa Rosa in August |
| September | 29° / 13° | 0 | 30 | 0 | 4 mm | Good | Santa Rosa in September |
| October | 24° / 11° | 3 | 28 | 0 | 55 mm | Perfect | Santa Rosa in October |
| November | 18° / 8° | 3 | 27 | 0 | 72 mm | Good | Santa Rosa in November |
| December | 13° / 5° | 6 | 25 | 0 | 119 mm | Ok | Santa Rosa in December |