Click on a day for an hourly weather forecast
The temperatures in Napa in August are comfortable with low of 15°C and and high up to 29°C.
You can expect up to 3 rainy days in Napa during the month of August.
Our weather forecast can give you a great sense of what weather to expect in Napa in August 2025.
If you’re planning to visit Napa in the near future, we highly recommend that you review the 14 day weather forecast for Napa before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | 15° / 7° | 5 | 26 | 0 | 121 mm | Good | Napa in January |
| February | 16° / 7° | 4 | 24 | 0 | 111 mm | Good | Napa in February |
| March | 17° / 8° | 6 | 25 | 0 | 103 mm | Good | Napa in March |
| April | 20° / 9° | 3 | 28 | 0 | 41 mm | Good | Napa in April |
| May | 23° / 11° | 2 | 29 | 0 | 25 mm | Perfect | Napa in May |
| June | 27° / 13° | 1 | 29 | 0 | 7 mm | Perfect | Napa in June |
| July | 29° / 14° | 0 | 31 | 0 | 2 mm | Good | Napa in July |
| August | 29° / 15° | 0 | 31 | 0 | 2 mm | Good | Napa in August |
| September | 29° / 15° | 0 | 30 | 0 | 3 mm | Good | Napa in September |
| October | 24° / 14° | 2 | 29 | 0 | 47 mm | Perfect | Napa in October |
| November | 18° / 10° | 3 | 27 | 0 | 65 mm | Good | Napa in November |
| December | 14° / 7° | 5 | 26 | 0 | 96 mm | Good | Napa in December |