Climate averages 1991–2020
Santa Rosa, United States weather
in January.
A cool, wet month: the 11th warmest and the 10th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
January is a cool month in Santa Rosa, United States: daytime highs average 14.4°C and nights cool to about 4.2°C. By daytime temperature it is the 11th warmest of the 12 months.
Expect about 145 mm of rain on roughly 10 days, which makes January a wet month (the 10th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 9 h 49 min on an average January day.
The nearest other city in this atlas is Napa (41 km away). In January its highs average 14.4°C, about as warm as Santa Rosa, United States, with 116 mm of rain.
Among the 498 cities listed in the United States, Santa Rosa, United States ranks joint 147th of 498 for the warmest January highs and 479th of 498 for the driest January (rainfall, lowest first). The mean January high of those 498 cities is 9.5°C; Santa Rosa, United States is 4.9°C warmer than that mean.
From January to February, average highs rise by 1.3°C to 15.7°C, and monthly rainfall rises from 145 mm to 149 mm.
The annual picture
January in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Santa Rosa, United States climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January, selected | 14.4°C4.2°C | 4.2°C | 145 | 10.3 | 9.810 h |
| February | 15.7°C5.0°C | 5.0°C | 149 | 9.5 | 10.711 h |
| March | 17.5°C6.3°C | 6.3°C | 112 | 9.5 | 11.912 h |
| April | 19.8°C7.8°C | 7.8°C | 49 | 5.6 | 13.213 h |
| May | 23.6°C10.6°C | 10.6°C | 28 | 3.6 | 14.214 h |
| June | 27.8°C13.1°C | 13.1°C | 7.0 | 1.2 | 14.815 h |
| July | 29.6°C14.1°C | 14.1°C | 0.4 | 0.1 | 14.615 h |
| August | 29.5°C14.3°C | 14.3°C | 1.1 | 0.2 | 13.714 h |
| September | 28.4°C13.6°C | 13.6°C | 3.1 | 0.6 | 12.512 h |
| October | 24.4°C11.2°C | 11.2°C | 34 | 3.2 | 11.211 h |
| November | 18.0°C7.0°C | 7.0°C | 75 | 6.2 | 10.110 h |
| December | 14.0°C4.2°C | 4.2°C | 150 | 10.2 | 9.510 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
January in nearby cities
- Napa in JanuaryUnited States · 41 kmHigh 14.4°C · Low 5.3°C · 116 mm rain
- Vallejo in JanuaryUnited States · 55 kmHigh 14.0°C · Low 5.1°C · 101 mm rain
- Fairfield in JanuaryUnited States · 63 kmHigh 13.7°C · Low 5.4°C · 109 mm rain
- Vacaville in JanuaryUnited States · 64 kmHigh 14.0°C · Low 5.4°C · 109 mm rain
- Berkeley in JanuaryUnited States · 74 kmHigh 13.7°C · Low 5.4°C · 93 mm rain
- San Francisco in JanuaryUnited States · 78 kmHigh 13.6°C · Low 6.1°C · 109 mm rain
- Concord (California), United States in JanuaryUnited States · 79 kmHigh 13.9°C · Low 5.6°C · 93 mm rain
- Oakland in JanuaryUnited States · 81 kmHigh 14.0°C · Low 5.7°C · 93 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Santa Rosa) is explained once on the Santa Rosa, United States year overview and on the Sources, method and limits page.