Napa, CA

Climate overview — based on NOAA 1991-2020 normals from NAPA STATE HOSPITAL, CA US.

Csb Warm-summer Mediterranean climate 9a USDA hardiness Zone 9a

Year-round temperatures (°F)

30° 50° 70° 90° J F M A M J J A S O N D
Avg high Avg low

Climate summary

Napa has an annual average temperature of 60.3°F with about 26.7 inches of precipitation per year. The warmest month is September (average high 84.4°F), and the coldest is December (average low 39.7°F). December is typically the wettest month (5.53 in) and July the driest (0.00 in).

Annual swing
20.5°F
warmest to coldest month
Heating need
2,187
Cooling need
477

Best time to visit Napa

Full guide →

Climate change signal

All-time records →

40 of 366 (10.9%) of Napa's all-time daily heat records have been set since 2015. If records were spread evenly across the station's history, only about 5% would fall in any given decade.

1890s
14
1900s
21
1910s
15
1920s
42
1930s
34
1940s
27
1950s
31
1960s
32
1970s
26
1980s
27
1990s
20
2000s
30
2010s
20
2020s
27

Bars: number of all-time daily heat records still standing that were set in each decade.

Monthly averages

Month Avg High Avg Low Avg Temp Precipitation Snow Rainy days
January 58.6°F 40.1°F 49.4°F 4.98 in 12
February 63.2°F 41.9°F 52.5°F 5.13 in 11
March 67.5°F 43.6°F 55.5°F 3.67 in 10
April 72.1°F 45.6°F 58.8°F 1.72 in 7
May 76.6°F 49.9°F 63.2°F 1.08 in 4
June 82.3°F 53.7°F 68.0°F 0.29 in 1
July 83.3°F 55.5°F 69.4°F 0.00 in 0
August 83.7°F 55.5°F 69.6°F 0.06 in 0
September 84.4°F 53.4°F 68.9°F 0.09 in 1
October 78.1°F 49.3°F 63.7°F 1.34 in 4
November 66.2°F 43.6°F 54.9°F 2.77 in 8
December 58.5°F 39.7°F 49.1°F 5.53 in 12

Climate twins of Napa

Why these? →

The most climatically similar US cities at least 140 miles away (by monthly temperature + precipitation pattern).

Frost dates
Last spring / first fall frost
All-time records
Hottest, coldest, wettest
Planting calendar
What to plant, and when

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