Santa Rosa, California Weather
Ceanothus blooms again. Day 93 of summer. Read this microseason across nine climate regions →
Santa Rosa weather forecast — hour by hour, 7-day outlook, NOAA radar
Conditions updated 7:25 AM PDT · Open-Meteo
- TodaySep 21Foggy——74°52°—
- TuesdaySep 22Foggy——83°50°+9°
- WednesdaySep 23Overcast——89°58°+6°
- ThursdaySep 24Overcast——87°62°-2°
- FridaySep 25Overcast——83°58°-4°
- SaturdaySep 26Overcast——81°57°-2°
- SundaySep 27Overcast——82°55°+1°
Air quality now AQI 32 · Good
AQI 32 (Good), driven by PM2.5. AQI flat over the last 6 hours (within ±3 points). PM2.5 at 5.3 µg/m³ (AQI 29) with a 0.77 fine-to-coarse ratio and 2 mph wind — combustion smoke trapped in stagnant air, not road dust.
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion.
What's driving it
PM × Wind × Precip
PM2.5 at 5.3 µg/m³ (AQI 29) with a 0.77 fine-to-coarse ratio and 2 mph wind — combustion smoke trapped in stagnant air, not road dust.
- PM2.5/PM10
- 0.77
- Wind
- calm
- Recent rain
- 0h in last 6h
- Pattern
- stagnant smoke
Trends
Seven days of AQI and PM2.5.
Hourly air-quality data from the Copernicus Atmosphere Monitoring Service, charted across the past and next several days. Dashed lines mark the AQI breakpoints at 50 (Good → Moderate) and 100 (Moderate → Unhealthy for Sensitive Groups).
September dries up ditches or breaks down bridges.
- Moonrise
- 4:42 PM
- Moonset
- 1:43 AM
- In sign
- ♑︎ Capricorn
Ceanothus blooms again
Read this microseason across nine climate regions →
All 72 microseasons on the year wheel →
Santa Rosa at a glance
- Today vs. normal: Today averages 63°F (high 74°F, low 52°F), 4°F below the 67°F normal for Sep 21
- Last frost: February 25 (1991–2020 median, NOAA station 1 km away)
- Microseason: Sep 21–25
- Planting calendar: September — plant beans, squash, fall brassicas, carrots; harvest tomatoes, peppers, beans, summer squash, winter squash
16-Day Forecast — Santa Rosa
- Mon74°52°2%
- Tue83°50°1%
- Wed89°58°0%
- Thu87°62°0%
- Fri83°58°0%
- Sat81°57°0%
- Sun82°55°0%
- Mon87°58°0%
- Tue93°65°1%
- Wed96°67°4%
- Thu87°71°2%
- Fri96°76°6%
- Sat102°73°0%
- Sun91°64°0%
- Mon86°58°0%
- Tue82°61°0%
Forecast data from Open-Meteo (CC BY 4.0).
Live wind & temperature near Santa Rosa
Interactive wind and temperature map centered on Santa Rosa — it loads in your browser. Open the full weather map.
Right now in the garden
Peak growing season
As of September 21, the growing season is at its peak — the first frost (around December 1) is weeks away. Fall transplants go in about 10–12 weeks before the first frost, September 8 to September 22 here. This city's planting calendar for September: plant beans, squash, fall brassicas, and carrots; harvest tomatoes, peppers, beans, summer squash, and winter squash.
Sun & seasons in Santa Rosa
Santa Rosa sits in Sonoma County, where the year’s longest day runs 14h 51m of daylight and its shortest just 9h 29m — a swing of +5h 22m between the June and December solstices. Clocks spring forward on Sunday, March 8, 2026 and fall back on Sunday, November 1, 2026.
Los Angeles, the state’s largest city, lies about 383 miles to the SE. The nearest town Santa Rosa tracks is Vallejo, roughly 34 miles to the SE.
Air quality in Santa Rosa
Air quality in Santa Rosa’s county has trended cleaner since 2020; its cleanest year on record was 2025 (median AQI 9). See the full air-quality history for Santa Rosa.
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| February | lettuce, peas, spinach, radishes | radishes |
| March | lettuce, peas, spinach, radishes | lettuce, spinach, radishes |
| April | — | lettuce, peas, spinach, radishes |
| May | tomatoes, peppers, beans, squash | lettuce, peas, spinach, garlic |
| June | tomatoes, peppers, beans, squash | garlic |
| July | beans, squash | tomatoes, peppers, beans, summer squash |
| August | tomatoes, peppers, beans, squash | tomatoes, peppers, beans, summer squash, winter squash |
| September | beans, squash, fall brassicas, carrots | tomatoes, peppers, beans, summer squash, winter squash |
| October | garlic (overwinter) | tomatoes, peppers, beans, summer squash, winter squash |
| November | garlic (overwinter) | tomatoes, peppers, beans, summer squash, winter squash, fall brassicas, carrots |
| December | — | fall brassicas, carrots |
A year in weather
In Santa Rosa, August runs warmest near 68°F and December coldest around 49°F, while December is the wettest month (6.5 inches) and July the driest (0.0 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 49° | 5.8″ | 14 |
| February | 52° | 6.4″ | 13 |
| March | 54° | 4.3″ | 12 |
| April | 57° | 2.0″ | 8 |
| May | 61° | 1.3″ | 5 |
| June | 66° | 0.3″ | 1 |
| July | 67° | 0.0″ | 0 |
| August | 68° | 0.0″ | 0 |
| September | 68° | 0.1″ | 1 |
| October | 63° | 1.6″ | 4 |
| November | 55° | 3.3″ | 9 |
| December | 49° | 6.5″ | 13 |
Regional context
Similar climates Fulton, CA, Larkfield-Wikiup, CA, Rohnert Park, CA
Per NOAA NCEI 1991-2020 normals, Santa Rosa runs from a 49°F January mean to 67°F in July, an 18°F seasonal spread, with near 31.5 inches of precipitation across about 81 wet days.
Cool-season fronts carry Santa Rosa's rain: December logs 6.5 inches on 13.1 days, against July's 0.0 inches on 0.3 — winter does the heavy lifting in Santa Rosa. It is a winter-storm rhythm Santa Rosa shares with places like Fulton, CA, Larkfield-Wikiup, CA and Rohnert Park, CA.
Santa Rosa reaches its last hard frost near February 25; that is the cue for lettuce, chard, arugula, and mustard greens. Heat-demanding starts go out a fortnight on in Santa Rosa, after the soil warms and cold snaps clear. By December 1, frost is back in Santa Rosa — protect or harvest anything tender. That date is a median: Santa Rosa freezes sooner in half of years.
Similar climates: Fulton, CA, Larkfield-Wikiup, CA, Rohnert Park, CA, Sebastopol, CA, Sonoma State University, CA.
Frequently asked
- When does it freeze in Santa Rosa?
- Santa Rosa's last spring frost lands near February 25, and in Santa Rosa the first fall frost follows around December 1.
- What is the rainy season in Santa Rosa?
- Santa Rosa sees its heaviest rain in December (around 6.5 inches), part of roughly 32 inches a year.
- What is the warmest month in Santa Rosa?
- August is Santa Rosa's warmest month, averaging about 68°F.
- What is the coldest month in Santa Rosa?
- Santa Rosa bottoms out in December, with a mean near 49°F.
- When can I start a vegetable garden in Santa Rosa?
- Santa Rosa's last frost (February 25) cues hardy greens; in Santa Rosa, hold heat-lovers two weeks past.
- How many rainy days does Santa Rosa get?
- Santa Rosa records around 81 days of measurable precipitation annually.
- What hardiness zone is Santa Rosa?
- Santa Rosa sits in the USDA zone set by December lows near 49°F; the USDA ZIP tool gives the band.
- What is the 10-day forecast for Santa Rosa?
- Santa Rosa's extended outlook — daily high and low temperatures and precipitation chances for each upcoming day — is in the daily forecast above.
- Will it rain this week in Santa Rosa?
- See this week's day-by-day rain chances for Santa Rosa in the daily forecast above, and the next 24 hours in the hourly chart.
- What is the weather like right now in Santa Rosa?
- Current conditions for Santa Rosa and the next 24 hours — temperature, precipitation chance, and wind by the hour — are in the hourly forecast chart above.
- How often is the Santa Rosa forecast updated?
- The Santa Rosa forecast on this page is built from Open-Meteo weather-model data and refreshes regularly through the day.
- When are sunrise and sunset in Santa Rosa?
- Today's sunrise and sunset times for Santa Rosa are in the Almanac section above, along with civil dawn, civil dusk, and day length. Day length is longest near the summer solstice and shortest near the winter solstice.
- How accurate is the weather forecast for Santa Rosa?
- The next few days in Santa Rosa's forecast are the most reliable; accuracy declines beyond about a week as weather-model uncertainty grows.
Santa Rosa sits at 38.4°N; its climate zone is hot-summer Mediterranean (Köppen approximation).
ZIP codes in Santa Rosa
- 95401
- 95403
- 95404
- 95405
- 95406
- 95407
- 95409