Grass Valley, CA climate
Grass Valley has mild winters and warm summers, with plenty of rain. A typical July afternoon reaches 89°, a January night drops to 36°, and about 15 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Grass Valley feels like
Winter
Spring
Summer
Fall
Grass Valley weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 53° | 36° | 10.0" | 2.3" | 14 | 2 | 40° – 51° |
| February | 55° | 36° | 9.6" | 4.6" | 12 | 4 | 38° – 52° |
| March | 58° | 38° | 8.5" | 3.2" | 12 | 3 | 40° – 55° |
| April | 64° | 41° | 4.7" | 0.9" | 9 | 1 | 46° – 57° |
| May | 72° | 48° | 2.7" | 0 | 6 | 0 | 50° – 68° |
| June | 81° | 54° | 0.8" | 0 | 3 | 0 | 63° – 73° |
| July | 89° | 61° | 0.0" | 0 | 0 | 0 | 71° – 79° |
| August | 89° | 60° | 0.1" | 0 | 1 | 0 | 71° – 78° |
| September | 84° | 56° | 0.5" | 0 | 2 | 0 | 66° – 74° |
| October | 73° | 48° | 2.9" | 0 | 4 | 0 | 56° – 68° |
| November | 59° | 40° | 5.8" | 0.8" | 9 | 1 | 41° – 56° |
| December | 51° | 35° | 11.0" | 2.7" | 12 | 2 | 40° – 48° |
| Year | 69° | 46° | 56.5" | 14.5" | 85 | 13 |
“Wet days” have at least 0.01" of rain or melted snow. “Snow on ground” counts days with 1" or more. The 30-year range is the coldest and warmest that month’s average temperature got between 1991 and 2020.
Rain and snow in Grass Valley
Grass Valley gets 57 inches of rain and melted snow a year. December is the wettest month and July the driest. Rain or snow falls on about 85 days a year. Snow covers the ground about 13 days of the year.
About 218 frost-free days a year
In half of years the last 32° night comes by April 14 and the first one by November 20. That leaves about 218 frost-free days for gardens, longer than 81% of U.S. towns.
Heating and cooling a home in Grass Valley
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Grass Valley, 83% of that work is heating and 17% is cooling, so the furnace matters far more than the air conditioner.
Degree days measure how far each day’s average temperature falls below or rises above 65°, added up over a year. Source: NOAA station normals.
How Grass Valley compares
Compared with every U.S. town and city on TownTapestry, each counted once.
Warmer than it used to be
The last 30 years in Grass Valley averaged 0.6° warmer than the 1900s. The biggest change is in September (+1.8°). The shift is smaller than in 94% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Grass Valley’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. May swings the most: between 1991 and 2020 its average temperature ranged from 50° to 68°. August is the most reliable, staying within 7°.
Common questions about Grass Valley’s climate
What is the coldest month in Grass Valley?
December, with a typical high of 51° and a low of 35°.
What is the hottest month in Grass Valley?
July, with a typical high of 89° and a low of 61°. About 30 days a year reach 90°.
How much snow does Grass Valley get?
About 15 inches in a normal winter, most of it in February.
When is the first frost in Grass Valley?
In half of years the first 32° night comes by November 20, and the last spring frost by April 14.
What is the rainiest month in Grass Valley?
December, with 11.0 inches of rain and melted snow. The year totals 57 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Grass Valley itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Nevada City, CA (3 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.