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 1981 to 2010 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, 1981 to 2010
High °F Low °F   High °C Low °C
57 39 January 14 4
62 42 February 17 6
67 44 March 19 6
71 45 April 22 7
76 50 May 25 10
81 53 June 27 12
83 55 July 28 13
83 55 August 28 13
83 53 September 28 12
77 49 October 25 10
65 44 November 18 7
57 40 December 14 4
72 47 Year 22 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 to October.

Hotter weather occurs sporadically during those months, with 25 days reaching 90 and three 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 4 0 0
March 4 1 0
April 15 5 0
May 24 8 2
June 29 14 4
July 31 19 5
August 31 19 5
September 29 17 7
October 25 11 1
November 7 1 0
December 0 0 0
Year 204 95 25

How Often Napa Has Cool Temperatures

Most nights at Napa never get colder than 40 °F. From November to February, it averages 12 nights with frost, but the next day always warms up to at least 40 degrees and usually 50 (10 °C). Only about once a decade does really cold weather descend here, when the temperature drops to 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 18 5
February 11 2
March 9 0
April 5 0
May 1 0
June 0 0
July 0 0
August 0 0
September 0 0
October 1 0
November 10 1
December 17 5
Year 72 12
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. 1981-2010 U.S. Climate Normals. (Data Access. FTP.)

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