Santa Rosa, CA Climate & Monthly Averages
Santa Rosa has an oceanic climate. July is the hottest month, averaging 86° by day; December is the coldest at 58°.
To understand Santa Rosa, start with the wet season
Santa Rosa's year is organised around rain rather than temperature. 59% of its 28.6 inches (727 mm) annual total arrives in the December to February window, while July averages less than 1 mm. Temperatures move far less: 86°F (30°C) at the year's warmest against 58°F (15°C) at its coolest.
Where the rain falls in the calendar
4 months average under 20 mm of rain, the longest unbroken stretch running June through September. Warmth peaks in July: highs of 86°F (30°C), lows of 57°F (14°C). December sits at the other end of the year: 58°F (15°C) by day, 42°F (5°C) at night. The gridded 2015-2024 daily record for this location tops out at 116°F (46°C) and bottoms at 27°F (-3°C) - decade extremes, not all-time station records. Snowfall is rare but not unheard of.
Rainfall is strongly seasonal: 59% of the annual total falls in the December to February window, leaving July at less than 1 mm. Four of the twelve months pair mild highs with fewer than twelve wet days; the longest unbroken run is April through May.
More climate facts for Santa Rosa
- Hottest month: July - highs near 86°F (30°C)
- Coldest month: December - highs near 58°F (15°C)
- Decade extremes (2015-2024): 116°F (46°C) high · 27°F (-3°C) low
- Wettest month: January (11 rainy days) · Sunniest: July (13.5 h sun/day)
- Climate type: oceanic
- Annual swing: 11°C between the average warmest and coolest month · day to night: 13°C
- Average humidity: 68%
Follow the rain through Santa Rosa's year
Each card shows the average high and low. The bar places that month between Santa Rosa's coldest night and warmest afternoon.
January
- Rain
- 11 days
- Sunshine
- 6.5 h
- Daylight
- 9.8 h
February
- Rain
- 8 days
- Sunshine
- 8.6 h
- Daylight
- 10.7 h
March
- Rain
- 11 days
- Sunshine
- 9.1 h
- Daylight
- 11.8 h
April
- Rain
- 5 days
- Sunshine
- 11.2 h
- Daylight
- 13.2 h
May
- Rain
- 3 days
- Sunshine
- 12.6 h
- Daylight
- 14.2 h
June
- Rain
- 0 days
- Sunshine
- 13.4 h
- Daylight
- 14.8 h
July
- Rain
- 0 days
- Sunshine
- 13.5 h
- Daylight
- 14.6 h
August
- Rain
- 0 days
- Sunshine
- 12.5 h
- Daylight
- 13.6 h
September
- Rain
- 1 day
- Sunshine
- 11.4 h
- Daylight
- 12.4 h
October
- Rain
- 3 days
- Sunshine
- 9.6 h
- Daylight
- 11.1 h
November
- Rain
- 6 days
- Sunshine
- 8.2 h
- Daylight
- 10.0 h
December
- Rain
- 11 days
- Sunshine
- 6.3 h
- Daylight
- 9.5 h
Looking for warmer alternatives? Browse warm places by month, or compare Santa Rosa's coolest part of the year: December, January, February.
Working around Santa Rosa's rain pattern
Choose dates by rain, not just temperature
April to June and September to October is the sweet spot for Santa Rosa - the rains have stopped and the heat has not yet peaked. Expect 75°F (24°C) in the afternoon and around 3 days of rain in a typical month of it. For the same question asked the other way round, see where else is warm in April.
What to pack
Pack for Santa Rosa with light clothing for the warm months and rain gear if you travel around January. Note the gap between afternoon and night: July pairs 86°F (30°C) with 57°F (14°C).
How Santa Rosa compares for rain and warmth
- Afternoons run 13°C above the following night - a bigger day-to-night gap than 94% of the 3496 cities we track.
- 59% of the year's precipitation falls in its wettest three months - more seasonal than 91% of the 3496 cities we track.
- Rain or snow reaches the ground on 60 days a year - fewer wet days than all but 12% of the 3496 cities we track.
These comparisons use the same ten-year window for every city in the dataset.
Monthly temperature and rain table
| Month | High | Low | Rain days | Precipitation | Sunshine | Daylight | Wet-day chance | Humidity |
|---|---|---|---|---|---|---|---|---|
| January | 59° | 42° | 11 | 6.4 in | 6.5 h/day | 9.8 h | 36% | 80% |
| February | 62° | 42° | 8 | 4.9 in | 8.6 h/day | 10.7 h | 27% | 72% |
| March | 63° | 44° | 11 | 4.4 in | 9.1 h/day | 11.8 h | 35% | 75% |
| April | 69° | 47° | 5 | 1.6 in | 11.2 h/day | 13.2 h | 17% | 69% |
| May | 75° | 51° | 3 | 0.9 in | 12.6 h/day | 14.2 h | 9% | 66% |
| June | 83° | 56° | 0 | 0.1 in | 13.4 h/day | 14.8 h | 2% | 58% |
| July | 86° | 57° | 0 | 0.0 in | 13.5 h/day | 14.6 h | 1% | 60% |
| August | 86° | 58° | 0 | 0.0 in | 12.5 h/day | 13.6 h | 1% | 63% |
| September | 84° | 57° | 1 | 0.2 in | 11.4 h/day | 12.4 h | 3% | 61% |
| October | 78° | 53° | 3 | 1.6 in | 9.6 h/day | 11.1 h | 11% | 60% |
| November | 65° | 45° | 6 | 2.9 in | 8.2 h/day | 10.0 h | 21% | 70% |
| December | 58° | 42° | 11 | 5.5 in | 6.3 h/day | 9.5 h | 34% | 78% |
The wet and quieter seasons in Santa Rosa
Spring (March through May)
Through spring, Santa Rosa is mild and warm: 69°F (21°C) by day, 47°F (8°C) after dark, and expect showers on roughly 19 days across the season. Daylight is generous - around 11.0 hours of sun a day.
Summer (June through August)
Through summer, Santa Rosa runs hot: 85°F (29°C) by day, 57°F (14°C) after dark, and precipitation is essentially absent. Daylight is generous - around 13.1 hours of sun a day. With the moisture factored in, afternoons feel hotter than the reading suggests - the humidity and dew point converter shows why.
Fall (September through November)
Through fall, Santa Rosa settles into easy warmth: 76°F (24°C) by day, 51°F (11°C) after dark, and rain comes on about 11 days over the three months.
Winter (December through February)
Winter is crisp but comfortable here - highs near 60°F (15°C), nights near 42°F (6°C), and expect showers on roughly 30 days across the season.
Rain and seasonal questions about Santa Rosa
Is Santa Rosa cold in winter?
How often does it rain in Santa Rosa?
How sunny is Santa Rosa?
How much do temperatures drop at night in Santa Rosa?
Is Santa Rosa hot in summer?
Santa Rosa temperature extremes in the 2015–2024 dataset
Derived from ERA5 reanalysis data, 2015–2024. Official station records may differ. Need another precipitation unit? Use the rainfall converter.