Climate averages 1991–2020
Vacaville weather
in December.
A cool, wet month: the coolest and the 10th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
December is a cool month in Vacaville: daytime highs average 13.8°C and nights cool to about 5.8°C. By daytime temperature it is the coolest month of the year.
Expect about 101 mm of rain on roughly 9 days, which makes December a wet month (the 10th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 9 h 33 min on an average December day.
The nearest other city in this atlas is Fairfield (13 km away). In December its highs average 13.6°C, about as warm as Vacaville, with 101 mm of rain.
Among the 498 cities listed in the United States, Vacaville ranks joint 177th of 498 for the warmest December highs and joint 381st of 498 for the driest December (rainfall, lowest first). The mean December high of those 498 cities is 10.5°C; Vacaville is 3.2°C warmer than that mean.
From December to January, average highs rise by 0.2°C to 14.0°C, and monthly rainfall rises from 101 mm to 109 mm.
The annual picture
December 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
Vacaville climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 14.0°C5.4°C | 5.4°C | 109 | 9.2 | 9.810 h |
| February | 15.8°C6.4°C | 6.4°C | 108 | 9.1 | 10.711 h |
| March | 18.2°C7.7°C | 7.7°C | 79 | 8.2 | 11.912 h |
| April | 21.3°C9.4°C | 9.4°C | 34 | 4.8 | 13.213 h |
| May | 25.8°C12.2°C | 12.2°C | 18 | 3.2 | 14.214 h |
| June | 30.4°C14.8°C | 14.8°C | 4.2 | 0.9 | 14.815 h |
| July | 32.4°C15.7°C | 15.7°C | 0.4 | 0.1 | 14.615 h |
| August | 32.0°C15.7°C | 15.7°C | 1.0 | 0.2 | 13.714 h |
| September | 30.4°C15.3°C | 15.3°C | 1.5 | 0.4 | 12.512 h |
| October | 25.2°C12.9°C | 12.9°C | 24 | 2.7 | 11.211 h |
| November | 18.1°C8.6°C | 8.6°C | 50 | 5.8 | 10.110 h |
| December, selected | 13.8°C5.8°C | 5.8°C | 101 | 9.0 | 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
December in nearby cities
- Fairfield in DecemberUnited States · 13 kmHigh 13.6°C · Low 5.8°C · 101 mm rain
- Napa in DecemberUnited States · 27 kmHigh 14.2°C · Low 5.6°C · 110 mm rain
- Vallejo in DecemberUnited States · 37 kmHigh 13.9°C · Low 5.5°C · 95 mm rain
- Antioch in DecemberUnited States · 42 kmHigh 13.7°C · Low 6.3°C · 87 mm rain
- Concord (California), United States in DecemberUnited States · 42 kmHigh 13.8°C · Low 6.0°C · 84 mm rain
- Sacramento in DecemberUnited States · 50 kmHigh 13.3°C · Low 4.5°C · 113 mm rain
- Elk Grove in DecemberUnited States · 54 kmHigh 13.1°C · Low 4.5°C · 121 mm rain
- Berkeley in DecemberUnited States · 59 kmHigh 13.6°C · Low 5.7°C · 87 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 Vacaville) is explained once on the Vacaville year overview and on the Sources, method and limits page.
Fairfield lies in the same rainfall cell, so its rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.