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.
| 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 |
| 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).
| 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).
| 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.