Vacaville climate — normals and trends
Vacaville (United States) has a warm-summer mediterranean climate (Csb) under the Köppen-Geiger classification. Its mean annual temperature is 15.4 °C and it receives 507 mm of precipitation per year.
These figures are normals computed over 86 complete calendar years, from 1940 to 2025, using ERA5 reanalysis data from the Copernicus programme.
The warmest month is July (21.1 °C on average) and the coldest is January (8.7 °C). Rainfall peaks in January.
Vacaville averages 3 frost days, 59 hot days (≥ 30 °C) and 52 rainy days per year.
Vacaville has warmed by +1.6 °C between 1940 and 2025, or +0.19 °C per decade. This trend is statistically significant.
The number of frost days there went from about 5 to 1 per year over the period.
The hottest day of the period reached 44.6 °C (on 14 July 1972) and the coldest -6.1 °C (on 22 December 1990).
Data from ERA5 reanalysis (Copernicus Climate Change Service), redistributed under a CC-BY 4.0 licence. Normals are recomputed whenever the archive is updated.
Climate normals · ERA5
VacavilleCalifornia
- coords
- 38.36°, -121.99°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
15.4°C
Average daily high
22.1°C
Average daily low
9.8°C
Annual rainfall
507mm
Sunshine / day
10.5h
Mean relative humidity
66%
Average peak wind
14.8km/h
Seasonal range
12.4°C
Frost days (< 0 °C)
3 d/yr
Hot days (≥ 30 °C)
59 d/yr
Rainy days (≥ 1 mm)
52 d/yr
Annual snowfall
0.2 cm
Average feels-like high
21.1 °C
Average feels-like low
8.0 °C
Average peak gust
34.0 km/h
Tropical nights (≥ 20 °C)
1 d/yr
Solar radiation
18.7 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+1.6 °C
since 1940
+0.2 °C per decade · r² = 0.49 · p = < 0.001
Trend fitted by linear regression (ordinary least squares) on annual means. A trend is shown only when it is statistically significant (p < 0.05).
A climograph overlays rainfall (bars) and temperature (line): the standard reading in climatology, where you can see at a glance whether the warm season is also the dry one.
Records for the period
Hottest day
44.6 °C
14 July 1972
Coldest day
-6.1 °C
22 December 1990
Wettest day
104 mm
13 October 2009
Windiest day
42.9 km/h
3 December 1983
Strongest gust
114.1 km/h
23 December 1955
Hottest feels-like
46.6 °C
14 July 1972
Coldest feels-like
-10.4 °C
22 December 1990
Snowiest day
5.0 cm
4 January 1974
Sunniest day
14.2 h
6 July 2025
Normals computed over complete calendar years 1940–2025.
A specific year
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Across the whole year
Month by month
| High | vs. normal | Precipitation | vs. normal | |
|---|---|---|---|---|
| Jan | 16.0 °C | +2.6 °C | 15 mm | -88 mm |
| Feb | 16.8 °C | +1.0 °C | 164 mm | +71 mm |
| Mar | 17.9 °C | 0.0 °C | 63 mm | -12 mm |
| Apr | 22.3 °C | +1.2 °C | 6 mm | -29 mm |
| May | 27.2 °C | +2.5 °C | 1 mm | -14 mm |
| Jun | 27.5 °C | -0.7 °C | 0 mm | -4 mm |
| Jul | 27.1 °C | -2.9 °C | 0 mm | -0 mm |
| Aug | 30.8 °C | +1.1 °C | 0 mm | -1 mm |
| Sep | 28.5 °C | -0.3 °C | 2 mm | -2 mm |
| Oct | 23.2 °C | -1.2 °C | 47 mm | +22 mm |
| Nov | 17.8 °C | -0.1 °C | 82 mm | +21 mm |
| Dec | 12.8 °C | -0.8 °C | 71 mm | -19 mm |
The year's extremes
What was the weather like that day?
Your birthday, a wedding, a memorable trip: discover the actual weather for any date since 1940.
Frequently asked questions
What is the climate of Vacaville?
Vacaville has a warm-summer mediterranean climate (Köppen Csb). Over 1940-2025, the average annual temperature is 15.4 °C and it receives 507 mm of precipitation per year.
What is the hottest day ever recorded in Vacaville?
The hottest day measured in Vacaville between 1940 and 2025 was 14 July 1972, reaching 44.6 °C.
What is the coldest day in Vacaville?
The coldest day measured in Vacaville between 1940 and 2025 was 22 December 1990, at -6.1 °C.
Does it snow in Vacaville?
Almost never: Vacaville sees virtually no snow, with about 3 frost days per year.
Has the climate of Vacaville warmed?
Yes: Vacaville warmed by +1.6 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Vacaville?
The wettest day measured in Vacaville between 1940 and 2025 was 13 October 2009, with 104 mm of rain in 24 hours.
What was the windiest day in Vacaville?
The windiest day measured in Vacaville between 1940 and 2025 was 3 December 1983, with winds reaching 42.9 km/h.
What is the warmest month in Vacaville?
The warmest month in Vacaville is July (21.1 °C on average); the coldest is January (8.7 °C).
How much does it rain in Vacaville?
Vacaville receives on average 507 mm of precipitation per year, spread over about 52 rainy days.
Is it sunny in Vacaville?
Vacaville gets on average 10.5 hours of sunshine per day, roughly 3,833 hours per year over 1940-2025.
What is the biggest single-day snowfall in Vacaville?
The heaviest 24-hour snowfall measured in Vacaville between 1940 and 2025 was 4 January 1974, with 5.0 cm.
Are there tropical nights in Vacaville?
Yes: Vacaville has on average 1 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Vacaville?
In Vacaville, between 1940 and 2025, the highest apparent temperature reached 46.6 °C on 14 July 1972, and the lowest was -10.4 °C on 22 December 1990.
Compare Vacaville with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Vacaville