Santa Rosa Sonoma County, CA Climate: Temperature & Rain by Month
Temperature and precipitation from NOAA NCEI 1991–2020 normals →, plus PlainClimate's derived comfort score
30-year climate normals (1991-2020) from Santa Rosa Sonoma County's primary NOAA station, SANTA ROSA SONOMA CO AP.
The climate verdict for Santa Rosa Sonoma County
A compact 20.8°F seasonal swing gives Santa Rosa Sonoma County, California a steadier-than-extreme annual shape. NOAA reports an annual average of 58°F. It scores 85/100 for climate comfort (excellent), putting it in the top third of station-mapped location scores and exceeding 85% of them.
- 58°F
- yearly average temperature, NOAA normal
- 85/100
- comfort score, above 85% of station-mapped location scores
- 33.8"
- precipitation, annual total
- 263 days
- growing season, frost-free days
Santa Rosa Sonoma County: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USW00023213 · Santa Rosa Sonoma County, CA 58°F mean · 33.8" precip
TEMP-MILD · RANK-UPPER · PHOTO-FINISH · PRCP-MID · SWING-NARROW · COMF-TOP · LOAD-HEAT · STN-1 · BOOK-FULL
- TEMP-MILD 58°F
- RANK-UPPER #4,734
- PHOTO-FINISH ≈ Petaluma
- PRCP-MID 33.8"
- SWING-NARROW 21°F
- COMF-TOP 85/100
- LOAD-HEAT 2,904 HDD
- STN-1 USW00023213
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: Petaluma, CA ( -0.1 °F mean)
Instrument codes from this station's NOAA 1991–2020 normals, mean temperature, corpus warmth rank, photo-finish peer station, precipitation band, seasonal swing, comfort composite, degree-day load, and field book, not a livability rating.
Mean-temperature neighbourhood
Nationwide NOAA normal poles and nearest peers, not a reprint of every CA station list.
- Hot Hollister, CA 59°F
- Santa Rosa Sono… (this station) 58°F
- Cold Napa County, CA 58°F
- Near Petaluma, CA 58°F
- Near Graton, CA 58°F
Climate Living Index · Santa Rosa Sonoma County
Santa Rosa Sonoma County: 88/100 · grade A
Santa Rosa Sonoma County publishes 4 of 6 Living Index dimensions (NOAA annual/seasonal normals · NOAA daily multivariate normals); 2 missing weights rescale to 100.
PlainClimate-derived for Santa Rosa Sonoma County, not an official NOAA rating. Rankings still use Comfort Score 85/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Normal heat + freeze calendar | 0 calendar days | 100/100 · A |
| Frost-free season | 263 days/year | 93/100 · A |
| Precipitation balance | 33.8 in · 1.2 from 35 in | 93/100 · A |
| Annual temperature balance | 58.1°F · 9.4° from 67.5°F | 70/100 · B |
Santa Rosa Sonoma County · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
Santa Rosa Sonoma County is a temperate Köppen climate: Csb
Coldest-month mean 47.2°F and warmest-month mean 68.0°F place this station in temperate, dry-summer, warm summer climates (Csb). Class Csb is the Peel et al. (2007) label for this station's monthly mean temperature and precipitation normals: temperate, specifically temperate, dry-summer, warm summer.
- Köppen code
- Csb
- Group
- Temperate
- Warmest month
- 68.0°F
- Coldest month
- 47.2°F
Source: official public datasets monthly normals (1991–2020) at the city’s primary station. This is a station classification, not a mapped regional consensus.
National standing · heating-led station
Where Santa Rosa Sonoma County sits across the climate record
Three NOAA fields for Santa Rosa Sonoma County's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- 69th percentile warmth
- Mid-pack annual mean versus 6,861 station normals.
- Annual precipitation
- 46th percentile wetness
- Neither arid nor torrential versus 6,352 station totals.
- Seasonal temperature swing
- Narrower than 96%
- Warmest-to-coldest month gap for Santa Rosa Sonoma County is compact versus 6,861 complete station-years.
How Santa Rosa Sonoma County compares across U.S. station-mapped locations
Santa Rosa Sonoma County's comfort score vs. all station-mapped locations
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
85 Top 15% score exceeds 85% of 6,189 station-mapped location scores
- 0–10: 0 station-mapped locations (0%). Below this entry.
- 10–20: 0 station-mapped locations (0%). Below this entry.
- 20–30: 96 station-mapped locations (2%). Below this entry.
- 30–40: 280 station-mapped locations (5%). Below this entry.
- 40–50: 1,113 station-mapped locations (18%). Below this entry.
- 50–60: 1,329 station-mapped locations (21%). Below this entry.
- 60–70: 1,236 station-mapped locations (20%). Below this entry.
- 70–80: 650 station-mapped locations (11%). Below this entry.
- 80–90: 921 station-mapped locations (15%). This entry sits in this band.
- 90–100: 564 station-mapped locations (9%). Above this entry.
Source NOAA U.S. Climate Normals, PlainClimate comfort index · 1991–2020
Monthly Temperatures
Average daily high and low temperatures by month
| Month | Avg High | Avg Low | Mean | Precip | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|
| January | 58°F (14°C) | 38°F (3°C) | 48°F (9°C) | 6.7" | 9.1 | 0.0 |
| February | 62°F (17°C) | 39°F (4°C) | 51°F (10°C) | 6.7" | 5.0 | 0.0 |
| March | 65°F (18°C) | 41°F (5°C) | 53°F (12°C) | 4.6" | 1.2 | 0.0 |
| April | 69°F (21°C) | 43°F (6°C) | 56°F (13°C) | 2.1" | 0.5 | 0.6 |
| May | 75°F (24°C) | 47°F (8°C) | 61°F (16°C) | 1.3" | 0.0 | 2.0 |
| June | 82°F (28°C) | 50°F (10°C) | 66°F (19°C) | 0.3" | 0.0 | 6.1 |
| July | 84°F (29°C) | 52°F (11°C) | 68°F (20°C) | 0.0" | 0.0 | 6.6 |
| August | 84°F (29°C) | 52°F (11°C) | 68°F (20°C) | 0.1" | 0.0 | 7.3 |
| September | 83°F (29°C) | 50°F (10°C) | 67°F (19°C) | 0.1" | 0.0 | 7.8 |
| October | 77°F (25°C) | 46°F (8°C) | 61°F (16°C) | 1.6" | 0.2 | 3.1 |
| November | 65°F (19°C) | 40°F (5°C) | 53°F (12°C) | 3.6" | 4.1 | 0.0 |
| December | 58°F (14°C) | 37°F (3°C) | 47°F (8°C) | 6.8" | 10.9 | 0.0 |
The year, day by day
The calendar barely moves in Santa Rosa Sonoma County: no date carries a normal high of 90°F or a normal low at freezing. The year runs between 37°F near December 19 and 85°F near August 26.
No freezing date
Not one calendar date in the 1991–2020 record carries a normal low at or below 32°F. The coldest normal low of the year is 37°F around December 19.
Where the wet dates fall
The likeliest wet date is December 17, when 41% of years recorded at least a hundredth of an inch. The driest is July 28 at 1%. Summed across the calendar, that is about 76 wet dates a year.
The widest day
September 11 carries the biggest normal gap between afternoon and dawn, 34°F between the normal high and the normal low.
Look up any date
Any date's 1991–2020 normal for Santa Rosa Sonoma County.
Where Santa Rosa Sonoma County Stands Nationally
Daily temperature swings run wider than most of the country, peaking near 34°F between the normal high and low.
Santa Rosa Sonoma County earns one nationally notable standing (outer quintile) against 6,860 NOAA 1991–2020 normals stations, middle-of-the-pack metrics stay silent here.
Monthly Precipitation
Average monthly rainfall
12.3 days with precipitation
11.1 days with precipitation
11.0 days with precipitation
7.5 days with precipitation
3.7 days with precipitation
1.5 days with precipitation
0.3 days with precipitation
0.2 days with precipitation
1.7 days with precipitation
4.3 days with precipitation
9.3 days with precipitation
12.6 days with precipitation
Santa Rosa Sonoma County's wet season runs through the cold months
December, January and February carry 60% of the year's precipitation here, while June through August contribute 1%. That is the cool-season-dominant pattern of the West Coast and the higher inland West, where storm tracks swing south in winter and summer turns dry; the thermometer meanwhile shows an unusually narrow 20.8°F seasonal spread.
- Wettest month
- December, 6.8"
- Driest month
- July, 0.0"
- Wettest three months
- December, January, February (60% of the year)
Shares are computed from this station's own 1991-2020 monthly precipitation normals. A cool-season label means the December-February share reaches 35%. Where snow falls, the monthly figures above report liquid-equivalent precipitation, so a wet winter month is not necessarily a rainy one.
When it rains in Santa Rosa Sonoma County, it arrives in quantity
33.8" of precipitation falls across only about 76 wet days here, averaging 0.45 inches each. Fewer days carry more water: the year's total is delivered in comparatively heavy events rather than persistent damp.
- Days with measurable precipitation
- about 76 a year, 21% of all days
- Average depth per wet day
- 0.45 inches
- Most wet days
- December, about 13
- Fewest wet days
- August, about 0
A wet day is one recording at least 0.01 inches. These are 1991-2020 normals: they describe an average year, and a per-day average is not a forecast of any individual storm.
Frost Dates & Growing Season
First Fall Freeze
November 20
50% probability date
Last Spring Freeze
March 2
50% probability date
Growing Season
263 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
2,904
Higher = more heating needed
Cooling Degree Days
410
Higher = more cooling needed
Warmest Month
August
Coldest Month
December
Nationwide similar cities
Other rankable U.S. places outside CA closest to Santa Rosa Sonoma County on two NOAA annual-normal axes (mean temperature and annual precipitation). Chip rows use distinct link sets.
Closest by average temperature
Nearest out-of-state peers by annual mean temperature (58°F here).
- Cairo, IL 58°F · 0.0°F off
- Dickson, TN 58°F · 0.0°F off
- Henderson, TN 58°F · 0.0°F off
- Hillsboro, NM 58°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (33.8" here), excluding temperature-peer places.
- Grantsburg, WI 33.8" · 0.0" off
- Minocqua, WI 33.8" · 0.0" off
- Newton, KS 33.8" · 0.0" off
- Findlay, OH 33.8" · 0.0" off
Data-derived climate profile
How Santa Rosa Sonoma County's climate pattern fits together
heating led · moderate · low swing
Heating is the larger measured load in Santa Rosa Sonoma County, at 2,904 degree days versus 410 for cooling. Unlike a strongly continental record, however, its 20.8°F month-to-month range is compact; persistent cool-season demand matters more than a dramatic summer-to-winter reversal.
The frost-free window extends for about 263 days. That is a long calendar measure, but it is not a forecast and does not combine heat, rainfall, soil, or local elevation into a planting recommendation.
Temperature varies within a narrow 20.8°F band across the normal year. August and December mark the typical warm and cold ends of the calendar. The annual average is 58°F. Monthly rows still matter, but they refine a steady profile rather than reveal two climatic extremes.
Santa Rosa Sonoma County's 33.8 inches of annual precipitation falls in PlainClimate's middle band, so “wet” or “dry” is not the leading description. Snowfall is not added to the interpretation because its annual value is missing. Temperature balance and the calendar distribution carry more information than the annual moisture label alone.
These labels group NOAA 1991-2020 normals from Santa Rosa Sonoma County's primary station, so the winter figures are a thirty-year average and not a floor: a single hard season can run well below them. Treat each band as a descriptive range for Santa Rosa Sonoma County, not an official NOAA class or a year-ahead forecast.
Questions about Santa Rosa Sonoma County's climate
How much rain does Santa Rosa Sonoma County get? ▼
How many days above 90°F does Santa Rosa Sonoma County get? ▼
How much energy does heating and cooling require in Santa Rosa Sonoma County? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Santa Rosa Sonoma County's primary station: SANTA ROSA SONOMA CO AP (USW00023213). For informational purposes only.
Place identity: U.S. Census Bureau 2024 Gazetteer places. The conservative exact name-and-state crosswalk finds no Census place match, so PlainClimate treats this as a station-mapped location and does not claim it is a municipality. No exact Gazetteer row for Santa Rosa Sonoma County; facility counts that depend on place identity are therefore an upper bound, not a municipal census.
On this page every temperature, precipitation, and derived score for Santa Rosa Sonoma County comes from its primary NOAA station record. No figure on this page is typed in by an editor - each value is rendered from NOAA 1991-2020 U.S. Climate Normals. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 1991–2020 normals.