Napa Temperatures: Averages by Month





The numbers here tell you how hot and cold the weather usually is in Napa, California during each month of the year.

The average high and low temperatures are listed below for Napa, in both degrees Fahrenheit and Celsius.

Maximums and minimums are only part of the temperature picture. To fill in the rest, there's information on how many days a month get above or below a given temperature.

To find out how often it rises over 70, 80 or 90 °F monthly and annually in the heart of California's wine country, scroll down farther. There are also counts of nights with cool temperatures.

The first set of high and low temperatures are averages for 2010 to 2019. Everything else here is based on 1991 to 2020 weather.

10-year temperature averages for Napa, 2010 to 2019
High °F Low °F   High °C Low °C
60 40 January 15 5
64 41 February 18 5
68 43 March 20 6
74 47 April 23 8
76 50 May 24 10
83 54 June 28 12
83 56 July 28 13
82 56 August 28 13
85 54 September 30 12
79 50 October 26 10
67 43 November 19 6
59 40 December 15 4
73 48 Year 23 9
30-year temperature averages for Napa, 1991 to 2020
High °F Low °F   High °C Low °C
59 40 January 15 5
63 42 February 17 6
68 44 March 20 6
72 46 April 22 8
77 50 May 25 10
82 54 June 28 12
83 56 July 29 13
84 56 August 29 13
84 53 September 29 12
78 49 October 26 10
66 44 November 19 6
59 40 December 15 4
73 48 Year 23 9

Days of Hot Weather in Napa

Napa's ideal grape-growing weather is also pleasant for people. Summer days usually warm up to the 70s or 80s Fahrenheit, as does most of May and October.

Hotter weather occurs sporadically during those months, with 32 days reaching 90 and five of those on average making it to 100 °F (38 °C).

Days per month in Napa of at least 70, 80 or 90 °F
  70 °F
21 °C
80 °F
27 °C
90 °F
32 °C
January 1 0 0
February 5 0 0
March 11 2 0
April 17 6 1
May 25 9 3
June 29 17 6
July 31 20 6
August 31 21 6
September 30 20 8
October 26 13 3
November 8 1 0
December 1 0 0
Year 215 109 32

How Often Napa Has Cool Temperatures

Most nights at Napa never get colder than 40 °F. From November to February, it averages 13 nights with frost, but the next day always warms up to at least 40 degrees and usually 50 (10 °C). It's not normal for Napa to get as cold as 20 °F (-8 °C).

Days per month on average in Napa when the minimum temperature drops to at least 40 or 32 °F
  32 °F
0 °C
40 °F
4 °C
January 5 17
February 2 12
March 0 10
April 0 6
May 0 1
June 0 0
July 0 0
August 0 0
September 0 0
October 0 1
November 1 11
December 5 18
Year 13 76
References

Jay Lawrimore, Ron Ray, Scott Applequist, Bryant Korzeniewski, Matthew Menne. 2016. Global Summary of the Month and Year, Version 1.0. NOAA National Centers for Environmental Information.

NOAA National Centers for Environmental Information (NCEI). Climate Normals.

California Temperatures
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