Click on a day for an hourly weather forecast
The temperatures in Vallejo in September are comfortable with low of 15°C and and high up to 28°C.
You can expect up to 3 rainy days in Vallejo during the month of September.
Our weather forecast can give you a great sense of what weather to expect in Vallejo in September 2025.
If you’re planning to visit Vallejo in the near future, we highly recommend that you review the 14 day weather forecast for Vallejo before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | 15° / 6° | 5 | 27 | 0 | 59 mm | Good | Vallejo in January |
| February | 16° / 7° | 4 | 24 | 0 | 60 mm | Good | Vallejo in February |
| March | 17° / 7° | 5 | 26 | 0 | 58 mm | Good | Vallejo in March |
| April | 20° / 8° | 2 | 28 | 0 | 22 mm | Good | Vallejo in April |
| May | 22° / 10° | 1 | 30 | 0 | 13 mm | Good | Vallejo in May |
| June | 26° / 13° | 0 | 30 | 0 | 5 mm | Perfect | Vallejo in June |
| July | 27° / 13° | 0 | 31 | 0 | 2 mm | Perfect | Vallejo in July |
| August | 27° / 14° | 0 | 31 | 0 | 2 mm | Perfect | Vallejo in August |
| September | 28° / 15° | 0 | 30 | 0 | 3 mm | Perfect | Vallejo in September |
| October | 24° / 13° | 2 | 29 | 0 | 26 mm | Perfect | Vallejo in October |
| November | 18° / 9° | 3 | 27 | 0 | 35 mm | Good | Vallejo in November |
| December | 14° / 7° | 5 | 26 | 0 | 48 mm | Good | Vallejo in December |