Last updated: March 2, 2024
Under the Köppen–Geiger climate classification Santa Rosa features a warm-summer Mediterranean climate (Csb). Temperatures typically range between 9 °C (48 °F) and 22 °C (71 °F) through the year, but rarely can drop to -4 °C (26 °F) or can rise to as high as 41 °C (105 °F). The average annual precipitation amounts to about 668 mm (26.3 inches) and receives 50 rainy days on the 1 mm (0.04 inches) threshold annually. Santa Rosa enjoys an average of 3381 hours of sunshine throughout the year, and daylight varies from 9 hours 30 minutes to 14 hours 48 minutes per day.
The warmest months in Santa Rosa are June, July and August, with daily mean temperatures ranging from 21 to 22 °C (69 - 71 °F) throughout the day. The coldest temperatures usually occur in January, February and December, when daily mean temperatures range from 9 to 10 °C (48 - 50 °F) throughout the day. On average each year, Santa Rosa experiences 118 days above 25 °C (77.0 °F) and 6 days below 0 °C (32.0 °F).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Maximum | 24°C (75°F) |
26°C (80°F) |
28°C (83°F) |
31°C (89°F) |
35°C (96°F) |
40°C (105°F) |
38°C (101°F) |
38°C (101°F) |
41°C (105°F) |
35°C (96°F) |
28°C (83°F) |
23°C (73°F) |
| Mean maximum | 21°C (69°F) |
23°C (73°F) |
26°C (78°F) |
29°C (84°F) |
32°C (90°F) |
36°C (96°F) |
36°C (98°F) |
36°C (97°F) |
37°C (99°F) |
32°C (90°F) |
25°C (77°F) |
20°C (68°F) |
| Average high | 14°C (58°F) |
16°C (62°F) |
17°C (63°F) |
20°C (69°F) |
23°C (75°F) |
28°C (83°F) |
30°C (86°F) |
29°C (85°F) |
28°C (83°F) |
25°C (77°F) |
19°C (66°F) |
14°C (58°F) |
| Daily mean | 9°C (49°F) |
10°C (50°F) |
11°C (52°F) |
14°C (57°F) |
17°C (62°F) |
21°C (69°F) |
22°C (71°F) |
21°C (71°F) |
20°C (69°F) |
17°C (63°F) |
12°C (54°F) |
9°C (48°F) |
| Average low | 5°C (41°F) |
5°C (40°F) |
6°C (43°F) |
8°C (47°F) |
11°C (52°F) |
14°C (57°F) |
15°C (59°F) |
15°C (60°F) |
14°C (57°F) |
10°C (51°F) |
6°C (43°F) |
4°C (40°F) |
| Mean minimum | -1°C (31°F) |
-1°C (30°F) |
0°C (33°F) |
3°C (38°F) |
7°C (44°F) |
10°C (50°F) |
12°C (54°F) |
12°C (54°F) |
9°C (49°F) |
5°C (41°F) |
0°C (32°F) |
-1°C (31°F) |
| Minimum | -2°C (28°F) |
-4°C (26°F) |
-1°C (30°F) |
3°C (37°F) |
3°C (39°F) |
8°C (47°F) |
11°C (53°F) |
10°C (51°F) |
7°C (45°F) |
3°C (38°F) |
-1°C (30°F) |
-2°C (29°F) |
Compare temperature, precipitation, sunshine, UV index in Santa Rosa, California, United States with other places around the world.
Santa Rosa usually has the most precipitation in January, February and December, with an average of 8 rainy days and 132 mm (5.2 inches) of precipitation per month. The driest months in Santa Rosa are July, August and September. On average, 1 mm (0.0 inches) of precipitation falls during these months.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Average precipitation mm (inches) | 139 (5.5) | 155 (6.1) | 97 (3.8) | 45 (1.8) | 27 (1.1) | 2 (0.1) | 0 (0.0) | 0 (0.0) | 2 (0.1) | 41 (1.6) | 58 (2.3) | 101 (4.0) |
| Average precipitation days (≥ 1 mm) | 8 | 8 | 11 | 5 | 3 | 0 | 0 | 0 | 0 | 2 | 5 | 8 |
The sunniest months in Santa Rosa are May, June and July, when the sun shines an average of 12 hours 15 minutes a day. Least sunny months in Santa Rosa: January, February and December receive an average of 5 hours 53 minutes of sunshine daily.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mean monthly sunshine hours | 141 | 210 | 261 | 297 | 356 | 382 | 389 | 348 | 312 | 277 | 218 | 184 |
| Mean daily daylight hours | 9h 48m | 10h 45m | 11h 59m | 13h 14m | 14h 17m | 14h 48m | 14h 31m | 13h 34m | 12h 22m | 11h 8m | 10h 2m | 9h 30m |
Santa Rosa experiences the highest level of ultraviolet (UV) radiation in June, July and August, when the maximum UV index can reach values of 10 - 11, which corresponds to the Very High / Extreme category of sun exposure. January, November and December are in the Moderate exposure category. In these months, the maximum values of the UV index do not exceed 4. For more detailed information, check out our hourly Santa Rosa UV Index data.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV Index (month maximum) | 3 | 5 | 7 | 9 | 10 | 11 | 11 | 10 | 9 | 6 | 4 | 3 |
Discover in-depth weather details for every month in Santa Rosa. Click through the links below for comprehensive overviews of temperature trends, precipitation levels, sunshine hours, and solar UV radiation specifics. Whether planning a visit or simply curious about Santa Rosa's climate nuances, these monthly breakdowns provide the information you need for an informed understanding of what to expect throughout the year.
Each link leads to a detailed account of the typical weather conditions for that month, providing both locals and tourists with vital information to plan their daily activities, wardrobe, and travel itineraries accordingly.