Monthly climate guide
Napa weather in August
Expect very hot weather in Napa in August: afternoons reach about 32°C (90°F), while nights drop to around 14°C (57°F). Around 0 mm of rain falls over the month (very dry), and skies are mostly sunny. Daytime highs are about the same as July and 2°C warmer than September.
What stands out in August
- Rain is well below Napa's usual level (around 100% less).
- Just 60 km apart, but Napa runs about 9°C warmer than San Francisco this month.
- August brings late summer to Napa.
- Expect a big gap between day and night — about 18°C.
August is typically Napa's warmest month.
Avg high
32°C
90°F
Avg low
14°C
57°F
Rainfall
0 mm
very dry
Humidity
49%
relative
Sky
24%
cloud · mostly sunny
Napa weather by month
Show the monthly averages as a table
| Month | Avg high | Avg low | Rain | Humidity | Cloud cover |
|---|---|---|---|---|---|
| January | 14°C / 56°F | 4°C / 39°F | 116 mm | 83% | 55% |
| February | 15°C / 58°F | 4°C / 40°F | 114 mm | 79% | 47% |
| March | 16°C / 61°F | 6°C / 42°F | 119 mm | 81% | 55% |
| April | 19°C / 67°F | 7°C / 45°F | 39 mm | 75% | 44% |
| May | 23°C / 74°F | 9°C / 48°F | 18 mm | 68% | 37% |
| June | 29°C / 85°F | 12°C / 54°F | 8 mm | 54% | 22% |
| July | 32°C / 89°F | 14°C / 56°F | 0 mm | 48% | 19% |
| August | 32°C / 90°F | 14°C / 57°F | 0 mm | 49% | 24% |
| September | 31°C / 87°F | 14°C / 57°F | 4 mm | 48% | 22% |
| October | 26°C / 79°F | 11°C / 52°F | 27 mm | 52% | 29% |
| November | 18°C / 65°F | 7°C / 44°F | 71 mm | 68% | 43% |
| December | 13°C / 56°F | 4°C / 39°F | 114 mm | 78% | 49% |
What to pack for August
- Light, breathable clothing (cotton or linen)
- A sun hat and high-SPF sunscreen
- A refillable water bottle
- An extra layer — evenings are noticeably cooler than afternoons
- Sunglasses
Is August a good time to visit Napa?
Compare the months in the chart above to find your ideal window.
Best time to visit Napa →Other United States cities in August
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Napa weather in August. WeatherCompare, 2026 (NASA POWER / ERA5, 2011–2020 monthly averages). https://weathercompare.eu/weather/usa/napa/august
<a href="https://weathercompare.eu/weather/usa/napa/august">Napa weather in August</a> (WeatherCompare)
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Napa in August: quick answers
Is August a good time to visit Napa?
It can be, if you like heat: August highs in Napa are around 32°C. Good for the beach; plan sightseeing for early morning and evening.
How warm is Napa in August?
Average highs are about 32°C (90°F) and average lows about 14°C (57°F), based on 10 years of daily data.
Does it rain a lot in Napa in August?
Napa typically gets around 0 mm of rain in August — very dry.
Figures are long-term averages for the area around Napa (NASA POWER / ERA5, 2011–2020), not a forecast for a specific year. For upcoming days, see the live multi-source forecast.