Sonoma, California climate: Normal weather by month, frost dates and records
Sonoma's normal year runs from 38°F December nights to 86°F July afternoons, with 28.4 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 15.0°C, December lows of 3°C, July highs of 30°C, 720 mm of precipitation a year.
- NOAA stationSonoma
- Station IDUSC00048351
- Location38.30°N 122.46°W
- Elevation97 ft (30 m)
- Population10,606
On October 23, the normal high in Sonoma is 75°F and the normal low 46°F, and the chance of measurable rain or snow is 14%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Sonoma.
- Jan 57° 38°
- Feb 62° 40°
- Mar 65° 42°
- Apr 69° 44°
- May 75° 48°
- Jun 83° 51°
- Jul 86° 54°
- Aug 86° 53°
- Sep 85° 51°
- Oct 78° 47°
- Nov 65° 42°
- Dec 57° 38°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Sonoma each month?
July is the warmest month, with normal highs of 86°F; December the coldest, with normal lows of 38°F. The most precipitation falls in December (5.83 in), the least in July (0.00 in).
Each month has its own page with the day-by-day normals, the month's records and its recent years:
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 57°F | 38°F | 47.7°F | 5.47 | 11 | <1 | 7 | 9 h 50 min |
| February | 62°F | 40°F | 50.8°F | 5.42 | 11 | <1 | 4 | 10 h 50 min |
| March | 65°F | 42°F | 53.7°F | 3.84 | 10 | <1 | 1 | 11 h 50 min |
| April | 69°F | 44°F | 56.7°F | 1.78 | 7 | <1 | <1 | 13 h 10 min |
| May | 75°F | 48°F | 61.6°F | 1.03 | 4 | 3 | <1 | 14 h 10 min |
| June | 83°F | 51°F | 67.1°F | 0.32 | 1 | 8 | <1 | 14 h 50 min |
| July | 86°F | 54°F | 69.7°F | 0.00 | <1 | 11 | <1 | 14 h 40 min |
| August | 86°F | 53°F | 69.6°F | 0.06 | <1 | 11 | <1 | 13 h 40 min |
| September | 85°F | 51°F | 68.0°F | 0.07 | 1 | 9 | <1 | 12 h 30 min |
| October | 78°F | 47°F | 62.5°F | 1.52 | 4 | 3 | <1 | 11 h 20 min |
| November | 65°F | 42°F | 53.5°F | 3.01 | 8 | <1 | 2 | 10 h 10 min |
| December | 57°F | 38°F | 47.4°F | 5.83 | 12 | <1 | 8 | 9 h 30 min |
| Year (annual) | 72°F | 46°F | 59.0°F | 28.35 | 68 | 44 | 21 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 14°C | 4°C | 8.7°C | 139 mm |
| February | 16°C | 5°C | 10.4°C | 138 mm |
| March | 19°C | 5°C | 12.1°C | 98 mm |
| April | 21°C | 7°C | 13.7°C | 45 mm |
| May | 24°C | 9°C | 16.4°C | 26 mm |
| June | 28°C | 11°C | 19.5°C | 8 mm |
| July | 30°C | 12°C | 20.9°C | 0 mm |
| August | 30°C | 12°C | 20.9°C | 2 mm |
| September | 29°C | 11°C | 20.0°C | 2 mm |
| October | 25°C | 9°C | 16.9°C | 39 mm |
| November | 18°C | 5°C | 11.9°C | 76 mm |
| December | 14°C | 3°C | 8.6°C | 148 mm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00048351; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
When is the best weather to visit Sonoma?
Normal highs sit between 65°F and 85°F in March, April, May, June, September, October and November. Of those, September has the fewest days with rain (1).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00048351.
When is the last frost in Sonoma?
In Sonoma, the last spring frost (32°F) comes after March 2 in half of years and after April 5 in one year in ten; the first autumn frost comes before November 27 in half of years and before November 6 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- March 21 year in 10 after April 5; 9 in 10 after January 27
- First autumn frost, half of years before
- November 271 year in 10 before November 6; 9 in 10 before December 21
NOAA puts the median frost-free season at 270 days, and the season without a hard freeze (28°F) at 334 days.
A hard freeze (28°F) comes after January 20 in half of springs and before December 14 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Sonoma in zone 9b in ZIP code 95476, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Sonoma's NOAA station is in zone 9b: the coldest night of a typical year reaches 26°F (26 complete years).
Frost dates for every NOAA station in California · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00048351; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
How hot and how cold does it get in Sonoma?
In a normal year in Sonoma, 44 days a year reach 90°F (7 of them 100°F or more), 21 nights fall to 32°F or colder and 68 days bring measurable precipitation.
- Days at 90°F or more
- 44a normal year
- Days at 100°F or more
- 7a normal year
- Nights at 32°F or colder
- 21a normal year
- Days that stay below freezing
- fewer than 1high of 32°F or less
- Days with 0.01 inch of precipitation
- 68a normal year
The highest temperature in this station's record (since 1893) is 116°F, on July 13, 1972; the lowest is 13°F, on December 22, 1990.
The wettest calendar year on that record is 1973, with 46.94 in.
Source: NOAA NCEI 1991-2020 annual normals, station USC00048351; records: ACIS (NOAA Regional Climate Centers), station USC00048351. Records use complete months only; a month missing more than three days is left out.
How sunny is Sonoma?
Over a year 87% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Sonoma, 5.1 kWh per square metre a day. July is the sunniest month (95%) and December the cloudiest (72%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 74% | 2.3 |
| February | 77% | 3.3 |
| March | 78% | 4.6 |
| April | 84% | 6.1 |
| May | 88% | 7.3 |
| June | 93% | 8.1 |
| July | 95% | 8.0 |
| August | 94% | 7.1 |
| September | 93% | 5.8 |
| October | 88% | 4.2 |
| November | 81% | 2.8 |
| December | 72% | 2.0 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How much heating and cooling does Sonoma need?
A normal year in Sonoma brings 2,748 heating degree days, 49% fewer than the median U.S. place (5,373), and 581 cooling degree days, 36% fewer than the median (908). Five months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 3,608 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 536 | 0 |
| February | 396 | 0 |
| March | 353 | 1 |
| April | 256 | 5 |
| May | 140 | 33 |
| June | 36 | 97 |
| July | 6 | 153 |
| August | 5 | 149 |
| September | 18 | 108 |
| October | 112 | 33 |
| November | 346 | 1 |
| December | 544 | 0 |
| Year (annual) | 2,748 | 581 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00048351. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Has Sonoma been warmer than normal lately?
2025 averaged 60.0°F, 1.0°F above the 1991-2020 normal of 59.0°F. 2 of the 2 complete years since 2024 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2024 | 60.8°F | +1.8°F | 30.98 |
| 2025 | 60.0°F | +1.0°F | 21.14 |
Source: observed years: ACIS, station USC00048351. A year counts only with all twelve months complete.
How does Sonoma's climate compare?
Sonoma is warmer than 75 of the other 218 places with their own NOAA record in California, and wetter than 164. Across the 7,247 U.S. stations with normals, its annual mean of 59.0°F is warmer than 72%.
In the Köppen classification computed from these normals, Sonoma is Csb: temperate, dry-summer, warm summer. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near Sonoma share this climate record?
7 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Boyes Hot Springs, CA7,031 people · 2 mi NW
- Fetters Hot Springs-Agua Caliente, CA3,441 people · 2 mi NW
- Yountville, CA3,280 people · 8 mi NE
- El Verano, CA3,154 people · 2 mi W
- Temelec, CA1,696 people · 3 mi SW
- Eldridge, CA1,126 people · 3 mi NW
- Glen Ellen, CA1,084 people · 6 mi NW
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
Questions about Sonoma's climate
What is the coldest month in Sonoma?
December, with a normal high of 57°F and a normal low of 38°F. The warmest is July (86°F by day, 54°F at night).
Does it snow in Sonoma?
Rarely: NOAA's normal is no measurable snow a year.
What is the rainiest month in Sonoma?
December, with 5.83 in of precipitation in a normal year; the driest is July with 0.00 in.
What plant hardiness zone is Sonoma in?
The USDA's 2023 map puts Sonoma in zone 9b in ZIP code 95476, the nearest ZIP area. By the same method at Sonoma's NOAA station, the coldest night of a typical year reaches 26°F (26 years, 1991-2020): zone 9b.
How late can frost come in Sonoma?
In half of years the last 32°F night comes after March 2; in one year in ten it comes after April 5. Waiting until April 5 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Sonoma in OctoberThis month day by day, its records and recent years
- California climateThe statewide normals and every place in the state
- Petaluma, CA9 miles from this station, 58.0°F a year
- Napa State Hospital, CA11 miles from this station, 60.3°F a year
- Napa, CA11 miles from this station, 57.7°F a year
- St. Helena, CA14 miles from this station, 61.0°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made