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The weather in Vacaville in September is hot. The average temperatures are between 16°C and 32°C. Usually the days in September are hot while the nights are a bit cooler.
You can expect a few rainy days in Vacaville during September, but usually the weather is comfortable in September.
Our weather forecast can give you a great sense of what weather to expect in Vacaville in September 2025.
If you’re planning to visit Vacaville in the near future, we highly recommend that you review the 14 day weather forecast for Vacaville before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | 14° / 5° | 6 | 25 | 0 | 106 mm | Good | Vacaville in January |
| February | 16° / 6° | 5 | 23 | 0 | 82 mm | Good | Vacaville in February |
| March | 18° / 7° | 6 | 25 | 0 | 95 mm | Good | Vacaville in March |
| April | 22° / 9° | 3 | 27 | 0 | 28 mm | Good | Vacaville in April |
| May | 26° / 11° | 2 | 29 | 0 | 16 mm | Perfect | Vacaville in May |
| June | 31° / 14° | 1 | 29 | 0 | 5 mm | Good | Vacaville in June |
| July | 33° / 15° | 0 | 31 | 0 | 1 mm | Good | Vacaville in July |
| August | 33° / 15° | 0 | 31 | 0 | 0 mm | Good | Vacaville in August |
| September | 32° / 16° | 1 | 30 | 0 | 4 mm | Good | Vacaville in September |
| October | 26° / 13° | 2 | 29 | 0 | 35 mm | Perfect | Vacaville in October |
| November | 18° / 8° | 4 | 26 | 0 | 46 mm | Good | Vacaville in November |
| December | 13° / 5° | 6 | 25 | 0 | 98 mm | Ok | Vacaville in December |