Vacaville in Winter
In winter (December, January and February), Vacaville sees average daytime highs around 59°F and overnight lows near 43°F, with 12.4 in of rain over about 27 wet days across the season. It is the coldest season of the year and the wettest season of the year.
Across winter, daytime highs hold fairly steady around 59°F. The sky is clear or mostly clear about 33% of the time across winter, and the air most often feels dry.
Winter is Vacaville's weakest season of the year to visit on our travel score. For the whole year in context, see Vacaville's year-round climate.
- Avg daytime high
- 59°F
- coldest season of the year
- Avg overnight low
- 43°F
- Rainfall
- 12.4 in
- 27 wet days
- Avg wind
- 5 mph
- Travel score
- 4.6
- weakest season of the year
- Months
- Dec · Jan · Feb
Temperature in Vacaville in Winter
Across winter, daytime highs hold fairly steady around 59°F.
A typical winter day in Vacaville reaches about 59°F and drops to 43°F overnight. The warmest of the three months is February, the coolest January.
Vacaville weather by month
How the three winter months (December, January and February) compare with the rest of the year — the season's months are highlighted.
| Month | High / Low (°F) | Rainfall (inches) | Wet days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|
| Jan | 58° / 42° | 4.3 | 9.2 | 9.6 | 4.3 |
| Feb | 62° / 44° | 4.2 | 9 | 10.5 | 5.2 |
| Mar | 66° / 46° | 3.1 | 8.2 | 11.7 | 6.4 |
| Apr | 71° / 49° | 1.3 | 4.8 | 13 | 7.5 |
| May | 77° / 53° | 0.7 | 3.2 | 14.1 | 8.4 |
| Jun | 83° / 57° | 0.2 | 0.9 | 14.6 | 7.7 |
| Jul | 85° / 58° | 0.0 | 0.1 | 14.4 | 7.1 |
| Aug | 85° / 58° | 0.0 | 0.2 | 13.5 | 7.1 |
| Sep | 84° / 57° | 0.1 | 0.4 | 12.3 | 7.7 |
| Oct | 77° / 53° | 0.9 | 2.7 | 11 | 8.5 |
| Nov | 65° / 47° | 2.0 | 5.8 | 9.9 | 6.6 |
| Dec | 58° / 42° | 3.9 | 9 | 9.4 | 4.3 |
Cloud cover in Winter
The sky is clear or mostly clear about 33% of the time across winter.
Chance of precipitation in Winter
Vacaville gets around 12.4 in of rain over 27 wet days across winter. The line is the day-by-day chance of measurable precipitation.
Humidity in Winter
Most of winter feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Winter
Winds average 5 mph across winter.
Sunrise & sunset in Winter
Daylight runs from about 9 h 30 min in early December to 11 hours by late February. The lit band spans sunrise to sunset each day.
Solar energy in Winter
Average shortwave solar energy reaching the ground each day across winter, about 2.5 kWh/m².
Hazard calendar for Vacaville
In winter, Vacaville overlaps its rainy season season. The full year is below, with each hazard's peak months called out.
Vacaville's rainy season runs November–March, when most of the year's rain falls.
Is winter a good time to visit Vacaville?
Our two travel scores rate winter for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
winter is a reasonable time to visit Vacaville for sightseeing.
What to pack for Vacaville in Winter
From winter's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In winter, Vacaville sees daytime highs around 59°F and nights near 43°F. Worth packing: a warm layer and rain gear. About 27 days see rain.
UV index in Vacaville in Winter
Clear-sky midday UV across winter averages around 3. The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in Vacaville peaks around June 23 at about 10 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 13 at about 2 (moderate).
The index reaches 3 or more — the level where the WHO recommends sun protection — in 9 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 2 | 4 | 5 | 6 | 8 | 10 | 10 | 9 | 6 | 5 | 2 | 2 |
| Level | Moderate | Moderate | Moderate | High | Very high | Very high | Very high | Very high | High | Moderate | Moderate | Low |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 2 | Moderate |
| Feb | 4 | Moderate |
| Mar | 5 | Moderate |
| Apr | 6 | High |
| May | 8 | Very high |
| Jun | 10 | Very high |
| Jul | 10 | Very high |
| Aug | 9 | Very high |
| Sep | 6 | High |
| Oct | 5 | Moderate |
| Nov | 2 | Moderate |
| Dec | 2 | Low |
Air quality in Vacaville in Winter
Average fine-particle pollution (PM2.5) through the year — so you can see where winter falls, not just the annual average.
Air quality in Vacaville is worst in September — around 29 µg/m³ PM2.5 (moderate), about 4.2× the cleanest month (June, 7 µg/m³).
Modeled monthly averages (CAMS reanalysis, 2015–2024).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 13 | 13 | 13 | 10 | 8 | 7 | 10 | 25 | 29 | 27 | 16 | 12 |
| Level | Moderate | Moderate | Moderate | Good | Good | Good | Good | Moderate | Moderate | Moderate | Moderate | Good |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 13 | Moderate |
| Feb | 13 | Moderate |
| Mar | 13 | Moderate |
| Apr | 10 | Good |
| May | 8 | Good |
| Jun | 7 | Good |
| Jul | 10 | Good |
| Aug | 25 | Moderate |
| Sep | 29 | Moderate |
| Oct | 27 | Moderate |
| Nov | 16 | Moderate |
| Dec | 12 | Good |
Where is Vacaville?
Vacaville sits at 38.4°N, 122.0°W, 174 ft above sea level, in United States. The nearest listed city is Fairfield, 8.1 mi away.
Topography around Vacaville
How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Vacaville.
Within 2 miles, the terrain around Vacaville has only modest variations in elevation — a maximum elevation change of 564 ft around an average of 210 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 2,825 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 4,459 ft.
The land around Vacaville is covered by artificial surfaces (47%), grassland (25%) and trees (23%) within 2 miles, grassland (41%), trees (25%) and cropland (20%) within 10 miles, and grassland (33%), trees (26%) and cropland (22%) within 50 miles.
United States travel facts
- Power plugs
- Type A / B
- 120 V · 60 Hz
- Prices
- ≈ 100% of US
- price level, 2025
- GDP per capita
- $90,027
- 2025
- Happiness
- 6.8 / 10
- World Happiness, 2025
- Safe drinking water
- 98%
- of population, 2024
- Homicide rate
- 5.8
- per 100k, 2023
- Road deaths
- 12.7
- per 100k/yr, 2019
- Income group
- High
- World Bank
- Religion
Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.
Data sources
Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Vacaville (38.3566°, -121.9877°, elevation 174 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google.