Napa County Climate
Napa County, California
Avg Annual Temp
59.5°F
Annual Precip
31.2"
Annual Snowfall
0.0"
Extreme Heat Days
48.5
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Seasonal Overview
National Comparison
Climate Profile
About Napa County Weather
Warm and Mediterranean
Napa County enjoys a warm 59.5°F annual average, placing it well above the national median temperature. This climate provides the ideal heat accumulation for world-class viticulture.
Warmer and Wetter Than Average
Napa is slightly warmer than the 58.7°F state average and notably wetter, receiving 31.2 inches of rain annually. This exceeds the California average of 25.8 inches, fueling its lush valley floor.
Hotter Summers Than Monterey
Compared to coastal Monterey, Napa is significantly warmer in the summer with a July average of 71.0°F. It also receives about 11 inches more rain per year than its southern coastal counterparts.
A Season of Sun and Rain
The county experiences 49 extreme heat days annually, marking a punishing summer season. Winters are wet but mild, with no recorded snowfall and a January average of 48.2°F.
Manage the Summer Heatwaves
Robust HVAC systems are a must to handle the 49 days of temperatures over 90°F. Homeowners should also maintain clear gutters to handle the 31.2 inches of concentrated winter rainfall.
Frequently Asked Questions
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Data source: NOAA National Centers for Environmental Information (NCEI), U.S. Climate Normals 1991-2020.
Climate normals are 30-year averages of weather variables computed from 1991 to 2020. Station data is aggregated to county level using spatial averaging. Data is informational only — not a substitute for official National Weather Service forecasts or emergency weather warnings.