Petaluma, California climate: Normal weather by month, frost dates and records
Petaluma's normal year runs from 38°F December nights to 81°F August afternoons, with 25.6 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 14.4°C, December lows of 4°C, August highs of 27°C, 649 mm of precipitation a year.
- NOAA stationPetaluma Airport
- Station IDUSC00046826
- Location38.26°N 122.61°W
- Elevation20 ft (6 m)
- Population59,393
On October 23, the normal high in Petaluma is 75°F and the normal low 47°F, and the chance of measurable rain or snow is 15%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Petaluma.
- Jan 58° 39°
- Feb 61° 40°
- Mar 65° 42°
- Apr 68° 44°
- May 72° 47°
- Jun 78° 50°
- Jul 81° 52°
- Aug 81° 53°
- Sep 82° 51°
- Oct 76° 48°
- Nov 66° 42°
- Dec 58° 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 Petaluma each month?
August is the warmest month, with normal highs of 81°F; December the coldest, with normal lows of 38°F. The most precipitation falls in February (5.23 in), the least in July (0.01 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 | 58°F | 39°F | 48.3°F | 4.77 | 12 | <1 | 6 | 9 h 50 min |
| February | 61°F | 40°F | 50.8°F | 5.23 | 11 | <1 | 3 | 10 h 50 min |
| March | 65°F | 42°F | 53.2°F | 3.32 | 10 | <1 | 1 | 11 h 50 min |
| April | 68°F | 44°F | 55.8°F | 1.68 | 6 | <1 | 1 | 13 h 10 min |
| May | 72°F | 47°F | 59.6°F | 0.93 | 4 | 1 | <1 | 14 h 10 min |
| June | 78°F | 50°F | 64.3°F | 0.28 | 1 | 3 | <1 | 14 h 50 min |
| July | 81°F | 52°F | 66.6°F | 0.01 | <1 | 4 | <1 | 14 h 40 min |
| August | 81°F | 53°F | 67.0°F | 0.05 | <1 | 4 | <1 | 13 h 40 min |
| September | 82°F | 51°F | 66.5°F | 0.09 | 1 | 6 | <1 | 12 h 30 min |
| October | 76°F | 48°F | 62.0°F | 1.27 | 4 | 2 | <1 | 11 h 20 min |
| November | 66°F | 42°F | 53.9°F | 2.74 | 8 | <1 | 3 | 10 h 10 min |
| December | 58°F | 38°F | 48.1°F | 5.19 | 12 | <1 | 8 | 9 h 30 min |
| Year (annual) | 70°F | 46°F | 58.0°F | 25.56 | 70 | 21 | 21 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 14°C | 4°C | 9.1°C | 121 mm |
| February | 16°C | 5°C | 10.4°C | 133 mm |
| March | 18°C | 5°C | 11.8°C | 84 mm |
| April | 20°C | 7°C | 13.2°C | 43 mm |
| May | 22°C | 9°C | 15.3°C | 24 mm |
| June | 26°C | 10°C | 17.9°C | 7 mm |
| July | 27°C | 11°C | 19.2°C | 0 mm |
| August | 27°C | 12°C | 19.4°C | 1 mm |
| September | 28°C | 11°C | 19.2°C | 2 mm |
| October | 25°C | 9°C | 16.7°C | 32 mm |
| November | 19°C | 6°C | 12.2°C | 70 mm |
| December | 14°C | 4°C | 8.9°C | 132 mm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00046826; 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 Petaluma?
Normal highs sit between 65°F and 85°F in April, May, June, July, August, September, October and November. Of those, July has the fewest days with rain (0).
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 USC00046826.
When is the last frost in Petaluma?
In Petaluma, the last spring frost (32°F) comes after February 28 in half of years and after April 6 in one year in ten; the first autumn frost comes before November 25 in half of years and before November 9 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
- February 281 year in 10 after April 6; 9 in 10 after January 24
- First autumn frost, half of years before
- November 251 year in 10 before November 9; 9 in 10 before December 16
NOAA puts the median frost-free season at 271 days, and the season without a hard freeze (28°F) at 331 days.
A hard freeze (28°F) comes after January 17 in half of springs and before December 9 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Petaluma in zone 9b in ZIP code 94954. By the map's own method, the average of each year's coldest night over 1991-2020, Petaluma's NOAA station is in zone 9b: the coldest night of a typical year reaches 26°F (23 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 USC00046826; 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 Petaluma?
In a normal year in Petaluma, 21 days a year reach 90°F (2 of them 100°F or more), 21 nights fall to 32°F or colder and 70 days bring measurable precipitation.
- Days at 90°F or more
- 21a normal year
- Days at 100°F or more
- 2a 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
- 70a normal year
The highest temperature in this station's record (since 1893) is 110°F, on June 2, 1960; the lowest is 16°F, on December 14, 1932.
The wettest calendar year on that record is 1940, with 44.18 in.
Source: NOAA NCEI 1991-2020 annual normals, station USC00046826; records: ACIS (NOAA Regional Climate Centers), station USC00046826. Records use complete months only; a month missing more than three days is left out.
How sunny is Petaluma?
Over a year 87% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Petaluma, 5.1 kWh per square metre a day. July is the sunniest month (95%) and December the cloudiest (72%). Among the 459 U.S. places of 50,000 or more, that ranks tied 58th (with 22 others) in sunshine.
| 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 Petaluma need?
A normal year in Petaluma brings 2,853 heating degree days, 47% fewer than the median U.S. place (5,373), and 317 cooling degree days, 65% 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 3,210 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 518 | 0 |
| February | 396 | 0 |
| March | 366 | 0 |
| April | 278 | 2 |
| May | 178 | 13 |
| June | 68 | 46 |
| July | 22 | 72 |
| August | 18 | 80 |
| September | 31 | 76 |
| October | 120 | 27 |
| November | 334 | 1 |
| December | 522 | 0 |
| Year (annual) | 2,853 | 317 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00046826. 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 Petaluma been warmer than normal lately?
2025 averaged 58.6°F, 0.6°F above the 1991-2020 normal of 58.0°F. 3 of the 3 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 58.5°F | +0.5°F | 21.91 |
| 2023 | 58.1°F | +0.1°F | 30.26 |
| 2025 | 58.6°F | +0.6°F | 19.25 |
Over 72 complete years from 1914 to 2025, the station's annual mean temperature rose at a fitted 2.8°F per century (+0.16°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00046826; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Petaluma's climate compare?
Petaluma is warmer than 61 of the other 218 places with their own NOAA record in California, and wetter than 158. Across the 7,247 U.S. stations with normals, its annual mean of 58.0°F is warmer than 69%.
In the Köppen classification computed from these normals, Petaluma 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 Petaluma share this climate record?
6 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.
- Rohnert Park, CA44,894 people · 8 mi NW
- Cotati, CA7,403 people · 7 mi NW
- Penngrove, CA2,123 people · 5 mi NW
- Sonoma State University, CA1,957 people · 7 mi NW
- Inverness, CA1,396 people · 18 mi SW
- Petaluma Center, CA815 people · 10 mi W
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 Petaluma's climate
What is the coldest month in Petaluma?
December, with a normal high of 58°F and a normal low of 38°F. The warmest is August (81°F by day, 53°F at night).
Does it snow in Petaluma?
Rarely: NOAA's normal is no measurable snow a year.
What is the rainiest month in Petaluma?
February, with 5.23 in of precipitation in a normal year; the driest is July with 0.01 in.
What plant hardiness zone is Petaluma in?
The USDA's 2023 map puts Petaluma in zone 9b in ZIP code 94954. By the same method at Petaluma's NOAA station, the coldest night of a typical year reaches 26°F (23 years, 1991-2020): zone 9b.
How late can frost come in Petaluma?
In half of years the last 32°F night comes after February 28; in one year in ten it comes after April 6. Waiting until April 6 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Petaluma in OctoberThis month day by day, its records and recent years
- California climateThe statewide normals and every place in the state
- Sonoma, CA9 miles from this station, 59.0°F a year
- Napa, CA18 miles from this station, 57.7°F a year
- San Rafael, CA19 miles from this station, 59.5°F a year
- Graton, CA19 miles from this station, 57.8°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made