Climate averages 1991–2020
Fairfield weather
in January.
A cool, wet month: the 11th warmest and the wettest of the year.
Long-term climate patterns, not a forecast for a particular trip.
January is a cool month in Fairfield: daytime highs average 13.7°C and nights cool to about 5.4°C. By daytime temperature it is the 11th warmest of the 12 months.
Expect about 109 mm of rain on roughly 9 days, which makes January a wet month (the wettest month of the year). Daylight, from sunrise to sunset, lasts about 9 h 50 min on an average January day.
The nearest other city in this atlas is Vacaville (13 km away). In January its highs average 14.0°C, about as warm as Fairfield, with 109 mm of rain.
Among the 498 cities listed in the United States, Fairfield ranks joint 180th of 498 for the warmest January highs and joint 441st of 498 for the driest January (rainfall, lowest first). The mean January high of those 498 cities is 9.5°C; Fairfield is 4.2°C warmer than that mean.
From January to February, average highs rise by 1.9°C to 15.5°C, and monthly rainfall falls from 109 mm to 108 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
Fairfield climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January, selected | 13.7°C5.4°C | 5.4°C | 109 | 9.2 | 9.810 h |
| February | 15.5°C6.4°C | 6.4°C | 108 | 9.1 | 10.711 h |
| March | 17.9°C7.7°C | 7.7°C | 79 | 8.2 | 11.912 h |
| April | 20.7°C9.1°C | 9.1°C | 34 | 4.8 | 13.213 h |
| May | 24.5°C11.4°C | 11.4°C | 18 | 3.2 | 14.214 h |
| June | 28.4°C13.5°C | 13.5°C | 4.2 | 0.9 | 14.815 h |
| July | 29.9°C14.3°C | 14.3°C | 0.4 | 0.1 | 14.515 h |
| August | 29.8°C14.6°C | 14.6°C | 1.0 | 0.2 | 13.614 h |
| September | 28.9°C14.3°C | 14.3°C | 1.5 | 0.4 | 12.512 h |
| October | 24.5°C12.5°C | 12.5°C | 24 | 2.7 | 11.211 h |
| November | 17.8°C8.7°C | 8.7°C | 50 | 5.8 | 10.110 h |
| December | 13.6°C5.8°C | 5.8°C | 101 | 9.0 | 9.610 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
- Vacaville in JanuaryUnited States · 13 kmHigh 14.0°C · Low 5.4°C · 109 mm rain
- Napa in JanuaryUnited States · 22 kmHigh 14.4°C · Low 5.3°C · 116 mm rain
- Vallejo in JanuaryUnited States · 25 kmHigh 14.0°C · Low 5.1°C · 101 mm rain
- Concord (California), United States in JanuaryUnited States · 30 kmHigh 13.9°C · Low 5.6°C · 93 mm rain
- Antioch in JanuaryUnited States · 34 kmHigh 13.9°C · Low 5.9°C · 93 mm rain
- Berkeley in JanuaryUnited States · 47 kmHigh 13.7°C · Low 5.4°C · 93 mm rain
- San Ramon in JanuaryUnited States · 52 kmHigh 13.8°C · Low 5.3°C · 89 mm rain
- Oakland in JanuaryUnited States · 53 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 Fairfield) is explained once on the Fairfield year overview and on the Sources, method and limits page.
Vacaville lies in the same rainfall cell, so its rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.