Santa Rosa climate
Santa Rosa (California, United States) has a hot-summer Mediterranean climate (Köppen Csa). The average temperature over the year is 16 °C61 °F, and about 688 mm27 in of precipitation falls in an average year.
Temperature by month
Precipitation by month
Santa Rosa climate table
| Month | High °C°F | Low °C°F | Mean °C°F | Precip. mmin |
|---|---|---|---|---|
| Jan | 1456 | 440 | 948 | 1204.7 |
| Feb | 1559 | 541 | 1050 | 1224.8 |
| Mar | 1763 | 643 | 1253 | 973.8 |
| Apr | 2067 | 745 | 1356 | 461.8 |
| May | 2475 | 1050 | 1763 | 220.9 |
| Jun | 3086 | 1355 | 2170 | 60.2 |
| Jul | 3391 | 1558 | 2475 | 10.0 |
| Aug | 3391 | 1458 | 2474 | 10.0 |
| Sep | 3188 | 1457 | 2272 | 30.1 |
| Oct | 2678 | 1152 | 1865 | 341.4 |
| Nov | 1865 | 744 | 1355 | 722.8 |
| Dec | 1356 | 440 | 948 | 1636.4 |
| Year | 3391 | 440 | 1661 | 68827 |
“Year” row: highest monthly high, lowest monthly low, annual mean and annual total.
| Month | Humid. | Cloud | Solar | Daylight |
|---|---|---|---|---|
| Jan | 84% | 55% | 2.3 | 9:46 |
| Feb | 82% | 53% | 3.3 | 10:42 |
| Mar | 81% | 52% | 4.6 | 11:51 |
| Apr | 76% | 44% | 6.1 | 13:09 |
| May | 69% | 35% | 7.3 | 14:15 |
| Jun | 56% | 22% | 8.1 | 14:50 |
| Jul | 49% | 19% | 8.0 | 14:35 |
| Aug | 49% | 21% | 7.1 | 13:39 |
| Sep | 47% | 21% | 5.8 | 12:23 |
| Oct | 54% | 31% | 4.2 | 11:07 |
| Nov | 70% | 45% | 2.8 | 10:01 |
| Dec | 82% | 57% | 2.0 | 9:30 |
Humid. = average relative humidity at 2 m; cloud = average cloud amount; solar = average daily solar energy reaching the ground in kWh/m² (all-sky); daylight in hours:minutes, calculated for the 15th of each month.
What the climate of Santa Rosa is like
The warmest month is July, with an average high of 33 °C91 °F and a low of 15 °C58 °F. The coldest is January, when highs average 14 °C56 °F and lows 4 °C40 °F. There is a clear seasonal cycle, with 14.9 °C26.7 °F between the average temperature of the warmest and the coolest month.
Annual precipitation is moderate at about 688 mm27 in. The wettest three-month stretch is December–February, which brings 59% of the annual total. Months with less than 20 mm0.8 in on average: June–September. The wettest month is December (163 mm6.4 in), the driest is August (1 mm0.0 in).
Relative humidity ranges from 47% in September to 84% in January. The clearest skies (lowest average cloud amount, 19%) are typical of July. Average wind speed near the ground ranges from 5 km/h (3 mph) in November to 7 km/h (4 mph) in June. Daylight lasts from about 9.5 hours in December to 14.8 hours in June.
Best time to visit Santa Rosa
Based on these averages, the most comfortable months for sightseeing and outdoor activities are April–June and October: average highs of 20 °C67 °F to 30 °C86 °F with 6 mm0.2 in to 46 mm1.8 in of precipitation per month.
The most challenging month is December, which is very wet (163 mm6.4 in).
Comfort score: months are ranked by how close they come to an average high of 21–28 °C (70–82 °F), lows above 5 °C (41 °F), little precipitation and moderate humidity. The best-ranked months of each place are recommended, even where none meets all of these. These are general rules of thumb applied to long-term averages.
What to pack for Santa Rosa
- Winter (December–February) — highs 1356 to 15 °C59 °F, lows 440 to 5 °C41 °F, about 135 mm5.3 in of precipitation a month. Pack long sleeves, a sweater and a medium jacket and an umbrella or light rain jacket.
- Spring (March–May) — highs 1763 to 24 °C75 °F, lows 643 to 10 °C50 °F, about 55 mm2.2 in of precipitation a month. Pack light layers — T-shirts plus a light sweater or jacket and an extra layer for the cooler mornings and evenings.
- Summer (June–August) — highs 3086 to 33 °C91 °F, lows 1355 to 15 °C58 °F, about 3 mm0.1 in of precipitation a month. Pack very light, breathable clothing, a sun hat and plenty of water and an extra layer for the cooler mornings and evenings.
- Autumn (September–November) — highs 1865 to 31 °C88 °F, lows 744 to 14 °C57 °F, about 37 mm1.4 in of precipitation a month. Pack light summer clothes such as T-shirts, shorts or light dresses and an extra layer for the cooler mornings and evenings.
How Santa Rosa compares
Compared with San Francisco, about 78 km to the south, Santa Rosa is on average 2 °C3.6 °F warmer and receives 18% more precipitation (688 mm27 in vs 586 mm23 in). The difference is largest in July (6.5 °C11.7 °F warmer).
Of the 222 places in the United States covered by World Climates, Santa Rosa is the 94th warmest by annual mean temperature and the 151st wettest by annual precipitation. See all of them on the United States climate page.
Places in other countries with the most similar temperature and rainfall pattern: Jerusalem (Israel, Csa), İzmir (Turkey, Csa) and Khouribga (Morocco, Csa).
Nearby places
- Vallejo 55 km · 14 °C57 °F · 586 mm23 in
- Fairfield 63 km · 15 °C60 °F · 467 mm18 in
- San Francisco 78 km · 14 °C57 °F · 586 mm23 in
- Concord 79 km · 15 °C59 °F · 467 mm18 in
- Daly City 85 km · 13 °C55 °F · 516 mm20 in
- Antioch 93 km · 15 °C60 °F · 467 mm18 in
- Hayward 102 km · 15 °C59 °F · 511 mm20 in
- Sacramento 107 km · 17 °C63 °F · 567 mm22 in
Frequently asked questions
What is the warmest month in Santa Rosa?
July is the warmest month in Santa Rosa, with an average high of 33 °C (91 °F) and an average low of 15 °C (58 °F).
What is the coldest month in Santa Rosa?
January is the coldest month, with an average high of 14 °C (56 °F) and an average low of 4 °C (40 °F).
When does it rain the most in Santa Rosa?
December is the wettest month with about 163 mm (6.4 in) of precipitation; August is the driest with about 1 mm (0.0 in).
What is the best time to visit Santa Rosa?
Judging by long-term averages, the most comfortable months are April–June and October.
About this data
All figures are 25-year averages (January 2001 – December 2025) from the NASA POWER project. Temperature, humidity, wind and precipitation come from the MERRA-2 reanalysis (precipitation is the bias-corrected MERRA-2 product), cloud and solar values from CERES satellite data. They describe a grid cell of roughly 50–70 km, not a single weather station, so they can differ from airport records — most of all on coasts, in mountains and for rainfall. Average highs and lows are the monthly mean temperature plus/minus half of the average daily temperature range. Counts of rainy days are not part of this dataset.
The grid cell’s average elevation is 266 m, while Santa Rosa lies at about 50 m. Temperatures on this page were therefore adjusted by +1.4 °C2.5 °F using the standard lapse rate of 6.5 °C per 1,000 m.