Santa Rosa Valley, CA climate
Santa Rosa Valley has warm winters and warm summers, with very little rain. A typical July afternoon reaches 85°, a January night drops to 44°, and snow is almost unheard of.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Santa Rosa Valley feels like
Winter
Spring
Summer
Fall
Santa Rosa 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 | 68° | 44° | 3.9" | 0 | 6 | 0 | 53° – 61° |
| February | 67° | 44° | 4.0" | 0 | 7 | 0 | 51° – 63° |
| March | 70° | 46° | 2.5" | 0 | 5 | 0 | 52° – 65° |
| April | 73° | 48° | 0.8" | 0 | 3 | 0 | 56° – 64° |
| May | 76° | 52° | 0.3" | 0 | 2 | 0 | 59° – 68° |
| June | 80° | 55° | 0.1" | 0 | 1 | 0 | 64° – 71° |
| July | 85° | 60° | 0.0" | 0 | 0 | 0 | 69° – 78° |
| August | 87° | 60° | 0.0" | 0 | 0 | 0 | 69° – 76° |
| September | 85° | 58° | 0.1" | 0 | 1 | 0 | 69° – 77° |
| October | 79° | 53° | 0.6" | 0 | 3 | 0 | 63° – 74° |
| November | 73° | 47° | 1.0" | 0 | 4 | 0 | 54° – 64° |
| December | 67° | 43° | 2.5" | 0 | 6 | 0 | 52° – 60° |
| Year | 76° | 51° | 15.8" | 0.0" | 36 | 0 |
“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 Santa Rosa Valley
Santa Rosa Valley gets 16 inches of rain and melted snow a year. February is the wettest month and August the driest. Rain or snow falls on about 36 days a year.
A year-round growing season
Heating and cooling a home in Santa Rosa Valley
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Santa Rosa Valley, 43% of that work is heating and 57% is cooling.
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.
Santa Rosa Valley and its neighbors
Santa Rosa Valley borders 2 towns with climate data. January nights across them vary by 1.7°. Moorpark has both the coldest January nights (43°) and the hottest July afternoons (86°). Santa Rosa Valley’s January low is 44° and its July high 85°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Santa Rosa 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 Santa Rosa Valley averaged 2.5° warmer than the 1900s. The biggest change is in January (+3.4°). The shift is larger than in 100% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Santa Rosa Valley’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. March swings the most: between 1991 and 2020 its average temperature ranged from 52° to 65°. June is the most reliable, staying within 7°.
Common questions about Santa Rosa Valley’s climate
What is the coldest month in Santa Rosa Valley?
December, with a typical high of 67° and a low of 43°.
What is the hottest month in Santa Rosa Valley?
August, with a typical high of 87° and a low of 60°. About 76 days a year reach 90°.
How much snow does Santa Rosa Valley get?
Almost none. A normal year brings 0.0 inches.
When is the first frost in Santa Rosa Valley?
Frost is uncommon. Only 18% of years see a night at 32° or below.
What is the rainiest month in Santa Rosa Valley?
February, with 4.0 inches of rain and melted snow. The year totals 16 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Santa Rosa Valley itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Northridge Cal State, CA (21 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.