Santa Rosa climate — normals and trends
Santa Rosa (United States) has a warm-summer mediterranean climate (Csb) under the Köppen-Geiger classification. Its mean annual temperature is 14.2 °C and it receives 726 mm of precipitation per year.
These figures are normals computed over 86 complete calendar years, from 1940 to 2025, using ERA5 reanalysis data from the Copernicus programme.
The warmest month is July (20.7 °C on average) and the coldest is January (7.7 °C). Rainfall peaks in January.
Santa Rosa averages 13 frost days, 45 hot days (≥ 30 °C) and 60 rainy days per year.
Santa Rosa has warmed by +1.6 °C between 1940 and 2025, or +0.19 °C per decade. This trend is statistically significant.
The number of frost days there went from about 19 to 7 per year over the period.
The hottest day of the period reached 42.5 °C (on 13 July 1972) and the coldest -5.6 °C (on 5 January 1974).
Data from ERA5 reanalysis (Copernicus Climate Change Service), redistributed under a CC-BY 4.0 licence. Normals are recomputed whenever the archive is updated.
Climate normals · ERA5
Santa RosaCalifornia
- coords
- 38.44°, -122.71°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
14.2°C
Average daily high
21.0°C
Average daily low
8.6°C
Annual rainfall
726mm
Sunshine / day
10.5h
Mean relative humidity
68%
Average peak wind
12.3km/h
Seasonal range
13.0°C
Frost days (< 0 °C)
13 d/yr
Hot days (≥ 30 °C)
45 d/yr
Rainy days (≥ 1 mm)
60 d/yr
Annual snowfall
1.7 cm
Average feels-like high
20.1 °C
Average feels-like low
6.9 °C
Average peak gust
34.9 km/h
Tropical nights (≥ 20 °C)
1 d/yr
Solar radiation
18.5 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+1.6 °C
since 1940
+0.2 °C per decade · r² = 0.49 · p = < 0.001
Trend fitted by linear regression (ordinary least squares) on annual means. A trend is shown only when it is statistically significant (p < 0.05).
A climograph overlays rainfall (bars) and temperature (line): the standard reading in climatology, where you can see at a glance whether the warm season is also the dry one.
Records for the period
Hottest day
42.5 °C
13 July 1972
Coldest day
-5.6 °C
5 January 1974
Wettest day
116 mm
24 October 2021
Windiest day
36.3 km/h
14 December 2002
Strongest gust
113.4 km/h
12 December 1995
Hottest feels-like
43.9 °C
14 June 2000
Coldest feels-like
-9.2 °C
3 February 1979
Snowiest day
15.3 cm
3 January 1974
Sunniest day
14.5 h
3 July 1940
Normals computed over complete calendar years 1940–2025.
A specific year
Pick a year and see how it compares to normal — warmer, drier or more extreme than usual?
Across the whole year
Month by month
| High | vs. normal | Precipitation | vs. normal | |
|---|---|---|---|---|
| Jan | 16.2 °C | +3.0 °C | 31 mm | -111 mm |
| Feb | 15.5 °C | +0.5 °C | 221 mm | +90 mm |
| Mar | 16.0 °C | -0.5 °C | 110 mm | +4 mm |
| Apr | 20.2 °C | +1.0 °C | 13 mm | -38 mm |
| May | 25.1 °C | +2.3 °C | 3 mm | -21 mm |
| Jun | 26.6 °C | 0.0 °C | 0 mm | -6 mm |
| Jul | 26.4 °C | -2.7 °C | 1 mm | -0 mm |
| Aug | 30.0 °C | +1.2 °C | 0 mm | -1 mm |
| Sep | 26.6 °C | -1.0 °C | 12 mm | +5 mm |
| Oct | 21.8 °C | -1.5 °C | 45 mm | +6 mm |
| Nov | 17.9 °C | +0.8 °C | 98 mm | +10 mm |
| Dec | 13.8 °C | +0.5 °C | 173 mm | +42 mm |
The year's extremes
What was the weather like that day?
Your birthday, a wedding, a memorable trip: discover the actual weather for any date since 1940.
Frequently asked questions
What is the climate of Santa Rosa?
Santa Rosa has a warm-summer mediterranean climate (Köppen Csb). Over 1940-2025, the average annual temperature is 14.2 °C and it receives 726 mm of precipitation per year.
What is the hottest day ever recorded in Santa Rosa?
The hottest day measured in Santa Rosa between 1940 and 2025 was 13 July 1972, reaching 42.5 °C.
What is the coldest day in Santa Rosa?
The coldest day measured in Santa Rosa between 1940 and 2025 was 5 January 1974, at -5.6 °C.
Does it snow in Santa Rosa?
Yes. Santa Rosa gets on average 1.7 cm of snow per year and has around 13 frost days.
Has the climate of Santa Rosa warmed?
Yes: Santa Rosa warmed by +1.6 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Santa Rosa?
The wettest day measured in Santa Rosa between 1940 and 2025 was 24 October 2021, with 116 mm of rain in 24 hours.
What was the windiest day in Santa Rosa?
The windiest day measured in Santa Rosa between 1940 and 2025 was 14 December 2002, with winds reaching 36.3 km/h.
What is the warmest month in Santa Rosa?
The warmest month in Santa Rosa is July (20.7 °C on average); the coldest is January (7.7 °C).
How much does it rain in Santa Rosa?
Santa Rosa receives on average 726 mm of precipitation per year, spread over about 60 rainy days.
Is it sunny in Santa Rosa?
Santa Rosa gets on average 10.5 hours of sunshine per day, roughly 3,833 hours per year over 1940-2025.
What is the biggest single-day snowfall in Santa Rosa?
The heaviest 24-hour snowfall measured in Santa Rosa between 1940 and 2025 was 3 January 1974, with 15.3 cm.
Are there tropical nights in Santa Rosa?
Yes: Santa Rosa has on average 1 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Santa Rosa?
In Santa Rosa, between 1940 and 2025, the highest apparent temperature reached 43.9 °C on 14 June 2000, and the lowest was -9.2 °C on 3 February 1979.
Compare Santa Rosa with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Santa Rosa