Santa Rosa Valley reaches 100° on about 14 days a year, more than 93% of U.S. towns
January mornings start at about 44°. From frosty January to warm July, readings climb 44°. Winters are mild: January nights here are milder than in 93% of U.S. towns. Picnics, hikes and garden evenings come into their own from October to June, with highs of 67–80°.
A year in Santa Rosa Valley at a glance
Each month’s typical high and low, and what it brings.
What stands out about Santa Rosa Valley’s climate
Compared with towns across the U.S., with Santa Rosa Valley’s place in California beside it.
What a year in Santa Rosa Valley feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 14 days a year reach 100°
And 76 days reach 90°. Frost and day counts come from NOAA’s station at Northridge Cal State, CA, 21 miles from the town’s center, 300 ft higher.
The 2023 USDA map puts Santa Rosa Valley’s center in zone 10a: the coldest night of a typical winter, averaged over 1991–2020, reaches about 34°. Plant labels use the zone; frost dates tell you when to plant.
90° days by month
Average days at 90° or more
About 16 inches of rain a year
February is the wettest month and August the driest. Rain falls on about 36 days a year. Snow is rare: about 0.0" in a normal year at Northridge Cal State, CA, so most winters see none.
Rain + melted snow by month
Inches of water
Heating and cooling a home in Santa Rosa Valley
43% of the work is heating, so air conditioning is the bigger bill. No month averages under 55°.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Northridge Cal State, CA.
Living with Santa Rosa Valley’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
Zone 10a. Frost comes about 1 winter in 5, so the growing year is set by heat, not cold: 14 days at 100° make midsummer the hard season for gardens.
Months with highs of 62–84° and lows of 40° or more: January, February, March, April, May, June, October, November and December. 18 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Santa Rosa Valley from natural hazards, river flooding is the largest share (61%). Normals are averages; the hazards page covers the extremes.
Natural hazards →Santa Rosa Valley and its neighbors
Every town next door is within a degree of Santa Rosa Valley in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Santa Rosa Valley’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Santa Rosa Valley, CA | 44° | 85° | 16" | 0.0" |
| Green, OR | 37° | 86° | 32" | 0.0" |
| Sierra Vista Southeast, AZ | 32° | 91° | 15" | 0.7" |
| Alpine, TX | 30° | 90° | 15" | 2.2" |
| Ewa Beach, HI | 62° | 87° | 17" | 0.0" |
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value. Snow and frost-free days come from the nearest weather station, so neighbors often share them.
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°).
A bigger shift than in all but 66 U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How Santa Rosa Valley compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Santa Rosa Valley’s place among California’s.
Santa Rosa Valley weather by month
Highs, lows and precipitation from NOAA’s grid at Santa Rosa Valley’s center; snow, wet days and snow on the ground from Northridge Cal State, CA. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 68° | 44° | 3.9" | 0.0" | 6 | 0 | 53° – 61° |
| February | 67° | 44° | 4.0" | 0.0" | 7 | 0 | 51° – 63° |
| March | 70° | 46° | 2.5" | 0.0" | 5 | 0 | 52° – 65° |
| April | 73° | 48° | 0.8" | 0.0" | 3 | 0 | 56° – 64° |
| May | 76° | 52° | 0.3" | 0.0" | 2 | 0 | 59° – 68° |
| June | 80° | 55° | 0.1" | 0.0" | 1 | 0 | 64° – 71° |
| July | 85° | 60° | 0.0" | 0.0" | 0 | 0 | 69° – 78° |
| August | 87° | 60° | 0.0" | 0.0" | 0 | 0 | 69° – 76° |
| September | 85° | 58° | 0.1" | 0.0" | 1 | 0 | 69° – 77° |
| October | 79° | 53° | 0.6" | 0.0" | 3 | 0 | 63° – 74° |
| November | 73° | 47° | 1.0" | 0.0" | 4 | 0 | 54° – 64° |
| December | 67° | 43° | 2.5" | 0.0" | 6 | 0 | 52° – 60° |
| Year | 76° | 51° | 15.8" | 0.0" | 36 | 0 |
How much a month can swing
A normal is an average. March swings the most: from 1991 to 2020 its average ranged from 52° to 65°. June is the most reliable, staying within 7°.
Where Santa Rosa Valley’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Santa Rosa Valley’s center.
- Snow: Northridge Cal State, CA.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Northridge Cal State, CA, 21 miles from the town’s center, 300 ft higher; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Santa Rosa Valley’s climate
What is the weather like in Santa Rosa Valley?
A typical July afternoon reaches 85°, a January night drops to 44°, and snow is almost unheard of. Milder January nights than 93% of U.S. towns; cooler July afternoons than 51% of U.S. towns.
How cold does it get in Santa Rosa Valley in winter?
December nights average 43°. A night at 32° or below comes in only some winters (0.6 a year on average). In the coldest December of the last 30 years the month averaged 52°.
How much snow does Santa Rosa Valley get?
About 0.0 inches in a normal winter at Northridge Cal State, CA, so most winters see none.
How hot does it get in Santa Rosa Valley?
July, with a typical high of 85° and a low of 60°. About 76 days a year reach 90° and 14 reach 100° (Northridge Cal State, CA).
When is the first and last frost in Santa Rosa Valley?
Most years have no frost at all: a 32° night comes in about 18% of winters at Northridge Cal State, CA, usually in December or January.
What growing zone is Santa Rosa Valley in?
Zone 10a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 34°.
What is the best time of year to visit Santa Rosa Valley?
By one simple rule (highs of 62–84° and lows of 40° or more), January, February, March, April, May, June, October, November and December. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Santa Rosa Valley getting warmer?
Yes: 1991–2020 averaged 2.5° warmer than 1901–2000 on NOAA’s grid. A bigger shift than all but 66 U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Santa Rosa Valley.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.