Napa Valley weather in August
Temperature, rain and sunshine in August: long-term averages from 30 years of weather data, not a forecast.
Holiday weather in August
Excellent
Best time to visit: April – October
What is the weather like in Napa Valley in August?
In August, Napa Valley is hot: daytime highs average 28 °C, and nights cool down to about 14 °C. With around 11 hours of sunshine a day, there is plenty of sun. It hardly ever rains. On about 9 days the thermometer climbs to 30 °C or more. All in all, August is an excellent month for a holiday in Napa Valley.
August compared
How the weather changes from July to September. Tap a month to open it.
| JulyJul | AugustAug | SeptemberSep | |
|---|---|---|---|
| Score | 93 | 91 | 96 |
| Day | 28° | 28° | 28° |
| Night | 13° | 14° | 14° |
| Sun | 12 h | 11 h | 10 h |
| Rain days | 0 | 0 | 1 |
More details for August
- Daylight
- 13 h 42 min06:23 – 20:05
- UV index
- 9 · very highclear sky, noon (estimate)All months
- Muggy days
- 0 daysdew point 18 °C or moreAll months
- Wind
- 15 km/haverage daily peakAll months
- Cloud cover
- 20 %on averageAll months
- Hot days
- 9 days30 °C or moreAll months
- Time zone
- UTC−7America/Los_Angeles
How the score comes together
- Temperatureweight 50 %83 %
- Sunshineweight 20 %100 %
- Few rainy daysweight 30 %100 %
Each factor is rated from 0 to 100 % and weighted for the travel style “Nature escape”.
What to pack in August
- Sunscreen
- Sunglasses & sun hat
- Light, breathable clothes
- Water bottle – drink plenty
- A jumper for the evenings
Napa Valley in August: quick answers
Is Napa Valley hot in August?
Yes. In August, Napa Valley is hot: daytime highs average 28 °C and nights stay around 14 °C. On about 9 days the thermometer climbs to 30 °C or more.
Does it rain much in Napa Valley in August?
It hardly ever rains.
Napa Valley month by month
The whole year in Napa ValleyAll destinations: USAWhere to go in August
Climate averages 1996–2025, not a forecast. Data: Copernicus ERA5 / ERA5-Land via Open-Meteo.com (CC BY 4.0), NOAA OISST, WMO 1991–2020 (NOAA NCEI), GeoNames (CC BY 4.0). Sources & licences