Grass Valley, OR climate
Grass Valley has chilly winters and warm summers, with very little rain. A typical July afternoon reaches 85°, a January night drops to 27°, and about 17 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 | 40° | 27° | 1.9" | 5.3" | 11 | 10 | 22° – 39° |
| February | 44° | 28° | 1.4" | 2.5" | 9 | 4 | 26° – 42° |
| March | 51° | 31° | 1.4" | 0.7" | 10 | 1 | 34° – 47° |
| April | 58° | 35° | 1.4" | 0 | 9 | 0 | 42° – 53° |
| May | 67° | 42° | 1.4" | 0 | 8 | 0 | 49° – 60° |
| June | 74° | 47° | 0.9" | 0 | 5 | 0 | 56° – 69° |
| July | 85° | 53° | 0.3" | 0 | 2 | 0 | 60° – 73° |
| August | 84° | 54° | 0.3" | 0 | 2 | 0 | 64° – 74° |
| September | 76° | 48° | 0.5" | 0 | 3 | 0 | 58° – 66° |
| October | 61° | 39° | 1.4" | 0.2" | 8 | 0 | 45° – 55° |
| November | 47° | 31° | 2.0" | 2.2" | 12 | 2 | 33° – 45° |
| December | 39° | 26° | 2.2" | 5.7" | 12 | 7 | 26° – 36° |
| Year | 60° | 38° | 15.0" | 16.6" | 90 | 24 |
“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 15 inches of rain and melted snow a year. December is the wettest month and July the driest. Rain or snow falls on about 90 days a year. Snow covers the ground about 24 days of the year.
About 143 frost-free days a year
In half of years the last 32° night comes by May 12 and the first one by October 4. That leaves about 143 frost-free days for gardens, shorter than 87% 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, 94% of that work is heating and 6% 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 1.4° warmer than the 1900s. The biggest change is in January (+3.9°). The shift is larger than in 64% 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. January swings the most: between 1991 and 2020 its average temperature ranged from 22° to 39°. September 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 39° and a low of 26°.
What is the hottest month in Grass Valley?
July, with a typical high of 85° and a low of 53°. About 22 days a year reach 90°.
How much snow does Grass Valley get?
About 17 inches in a normal winter, most of it in December.
When is the first frost in Grass Valley?
In half of years the first 32° night comes by October 4, and the last spring frost by May 12.
What is the rainiest month in Grass Valley?
December, with 2.2 inches of rain and melted snow. The year totals 15 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 Moro, OR (9 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.