Vacaville weather in December

In December, Vacaville sees average daytime highs of 58°F and overnight lows near 42°F, with 3.9 in of rain across 9 wet days and about 9.4 hours of daylight. It is the 11th-warmest and 3rd-wettest month of the year here.

Highs ease over the month, from about 60°F in the first days to 56°F by the end. The sky is clear or mostly clear about 34% of the time in December, and the air most often feels dry.

Daylight stretches from about 9 h 30 min at the start of December to 9 h 24 min by month's end. Set against the rest of the year, December is Vacaville's 10th-clearest and 10th-windiest month. For the whole year in context, see Vacaville's year-round climate.

Daytime high: 58°; 11th warmest
Overnight low: 42°; 2nd coldest
Rainfall: 3.9 in; 9 wet days
Daylight: 9 h 18 min; 7:24 AM – 4:44 PM
Cloud cover: 58%; 10th clearest
Wind: 5 mph; 10th windiest
Solar energy: 2.09 kWh/m²
Travel score: 4.3; out of 10

Vacaville is city in Solano County, California, United States of America.

Density: 1,308/km²; people per km²
Founded: 1852

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

← November Vacaville year-round climate January →Best places to visit in December

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Temperature in December

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 60°F in the first days to 56°F by the end.

A typical December day in Vacaville reaches about 58°F in the afternoon and slips back to 42°F overnight — a 15°F spread between the day's warmth and the night's chill. On most days the high lands between 52°F and 63°F. Set against its neighbours, December runs about 8°F cooler than November and on par with January.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Avg high (°F)	60	60	60	59	59	59	59	58	58	58	58	58	58	57	57	57	57	57	57	57	57	56	56	56	56	56	56	56	56	56	56
Avg low (°F)	44	44	44	44	44	44	43	43	43	43	43	43	43	43	42	42	42	42	42	42	42	42	42	41	41	41	41	41	41	41	41

	Avg high (°F)	Avg low (°F)
1	60	44
2	60	44
3	60	44
4	59	44
5	59	44
6	59	44
7	59	43
8	58	43
9	58	43
10	58	43
11	58	43
12	58	43
13	58	43
14	57	43
15	57	42
16	57	42
17	57	42
18	57	42
19	57	42
20	57	42
21	57	42
22	56	42
23	56	42
24	56	41
25	56	41
26	56	41
27	56	41
28	56	41
29	56	41
30	56	41
31	56	41

Vacaville weather by month

How December compares with the rest of the year at a glance. December is the 11th-warmest and 3rd-wettest month here — the current month is highlighted below.

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 December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 34% of the time in December.

Beyond those clear spells, partly cloudy skies cover about 11% of December, with mostly cloudy or overcast conditions the remaining 54%.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Clearer (%)	51	49	49	48	47	46	45	45	44	44	44	44	44	44	45	45	45	46	46	47	47	46	46	46	46	45	44	44	44	44	43
Cloudier (%)	49	51	51	52	53	54	55	55	56	56	56	56	56	56	55	55	55	54	54	53	53	54	54	54	54	55	56	56	56	56	57

	Clearer (%)	Cloudier (%)
1	51	49
2	49	51
3	49	51
4	48	52
5	47	53
6	46	54
7	45	55
8	45	55
9	44	56
10	44	56
11	44	56
12	44	56
13	44	56
14	44	56
15	45	55
16	45	55
17	45	55
18	46	54
19	46	54
20	47	53
21	47	53
22	46	54
23	46	54
24	46	54
25	46	54
26	45	55
27	44	56
28	44	56
29	44	56
30	44	56
31	43	57

Chance of precipitation in December

Any precipitation

Vacaville gets around 3.9 in of rain over 9 wet days in December. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 29% and peaks near 31% on the wettest days.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Rain chance (%)	27	28	28	29	30	30	30	31	31	31	31	31	31	31	30	30	29	29	28	28	28	28	28	28	27	27	27	27	27	27	28

	Rain chance (%)
1	27
2	28
3	28
4	29
5	30
6	30
7	30
8	31
9	31
10	31
11	31
12	31
13	31
14	31
15	30
16	30
17	29
18	29
19	28
20	28
21	28
22	28
23	28
24	28
25	27
26	27
27	27
28	27
29	27
30	27
31	28

Humidity in December

DryComfortableHumidMuggyOppressiveMiserable

Most of December feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, December lands in the dry band about 97% of days. It rarely turns muggy — the humid and sticky bands barely register.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Dry (%)	97	97	97	97	97	96	96	96	96	96	97	97	97	97	97	97	97	98	98	98	98	98	98	98	98	98	98	98	98	98	98
Comfortable (%)	3	3	3	3	3	4	4	4	4	4	3	3	3	3	3	3	3	2	2	2	2	2	2	2	2	2	2	2	2	2	2

	Dry (%)	Comfortable (%)
1	97	3
2	97	3
3	97	3
4	97	3
5	97	3
6	96	4
7	96	4
8	96	4
9	96	4
10	96	4
11	97	3
12	97	3
13	97	3
14	97	3
15	97	3
16	97	3
17	97	3
18	98	2
19	98	2
20	98	2
21	98	2
22	98	2
23	98	2
24	98	2
25	98	2
26	98	2
27	98	2
28	98	2
29	98	2
30	98	2
31	98	2

Wind in December

Winds average 5 mph in December.

Across December, daily wind ranges from about 5 mph on the calmest days to 5 mph at its breeziest. It stays fairly steady from day to day.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Wind speed (mph)	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5
Feels	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm

	Wind speed (mph)	Feels
1	5	calm
2	5	calm
3	5	calm
4	5	calm
5	5	calm
6	5	calm
7	5	calm
8	5	calm
9	5	calm
10	5	calm
11	5	calm
12	5	calm
13	5	calm
14	5	calm
15	5	calm
16	5	calm
17	5	calm
18	5	calm
19	5	calm
20	5	calm
21	5	calm
22	5	calm
23	5	calm
24	5	calm
25	5	calm
26	5	calm
27	5	calm
28	5	calm
29	5	calm
30	5	calm
31	5	calm

Sunrise & sunset in December

DaylightNight

Daylight runs from about 9 h 30 min at the start of December to 9 h 24 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 6 minutes over December. Sunrise moves from 7:12 AM to 7:30 AM, and sunset from 4:43 PM to 4:52 PM.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Daylight (h)	9.5	9.5	9.5	9.5	9.5	9.4	9.4	9.4	9.4	9.4	9.4	9.4	9.4	9.4	9.3	9.3	9.3	9.3	9.3	9.3	9.3	9.3	9.3	9.3	9.3	9.3	9.3	9.3	9.3	9.4	9.4
Sunrise (AM)	7:12	7:13	7:14	7:15	7:16	7:16	7:17	7:18	7:19	7:20	7:20	7:21	7:22	7:23	7:23	7:24	7:24	7:25	7:26	7:26	7:27	7:27	7:28	7:28	7:28	7:29	7:29	7:29	7:30	7:30	7:30
Sunset (PM)	4:43	4:43	4:43	4:43	4:43	4:43	4:43	4:43	4:43	4:43	4:43	4:43	4:44	4:44	4:44	4:44	4:45	4:45	4:45	4:46	4:46	4:47	4:47	4:48	4:48	4:49	4:49	4:50	4:51	4:51	4:52

	Daylight (h)	Sunrise (AM)	Sunset (PM)
1	9.5	7:12	4:43
2	9.5	7:13	4:43
3	9.5	7:14	4:43
4	9.5	7:15	4:43
5	9.5	7:16	4:43
6	9.4	7:16	4:43
7	9.4	7:17	4:43
8	9.4	7:18	4:43
9	9.4	7:19	4:43
10	9.4	7:20	4:43
11	9.4	7:20	4:43
12	9.4	7:21	4:43
13	9.4	7:22	4:44
14	9.4	7:23	4:44
15	9.3	7:23	4:44
16	9.3	7:24	4:44
17	9.3	7:24	4:45
18	9.3	7:25	4:45
19	9.3	7:26	4:45
20	9.3	7:26	4:46
21	9.3	7:27	4:46
22	9.3	7:27	4:47
23	9.3	7:28	4:47
24	9.3	7:28	4:48
25	9.3	7:28	4:48
26	9.3	7:29	4:49
27	9.3	7:29	4:49
28	9.3	7:29	4:50
29	9.3	7:30	4:51
30	9.4	7:30	4:51
31	9.4	7:30	4:52

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 2.09 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 2.09 kWh/m² to a high of 8.13 kWh/m² in July across the year — December's 2.09 kWh/m² sits near the bottom.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Solar energy (kWh/m²)	2.2	2.2	2.2	2.1	2.1	2.1	2.1	2.1	2.1	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.1	2.1	2.1	2.1	2.1	2.1	2.1	2.1	2.1	2.1	2.1
Level	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate

	Solar energy (kWh/m²)	Level
1	2.2	Moderate
2	2.2	Moderate
3	2.2	Moderate
4	2.1	Moderate
5	2.1	Moderate
6	2.1	Moderate
7	2.1	Moderate
8	2.1	Moderate
9	2.1	Moderate
10	2.0	Moderate
11	2.0	Moderate
12	2.0	Moderate
13	2.0	Moderate
14	2.0	Moderate
15	2.0	Moderate
16	2.0	Moderate
17	2.0	Moderate
18	2.0	Moderate
19	2.0	Moderate
20	2.0	Moderate
21	2.1	Moderate
22	2.1	Moderate
23	2.1	Moderate
24	2.1	Moderate
25	2.1	Moderate
26	2.1	Moderate
27	2.1	Moderate
28	2.1	Moderate
29	2.1	Moderate
30	2.1	Moderate
31	2.1	Moderate

Planning a trip in December

Hazard calendar for Vacaville

In seasonPeak

In December, Vacaville sits inside 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.

Rainy season

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Is December a good time to visit Vacaville?

Our two travel scores rate December for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

4.3

Sightseeing

11th-best month of the year

0.1

Beach & pool

11th-best month of the year

December is a reasonable time to visit Vacaville for sightseeing.

What to pack for Vacaville in December

From December's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In December, Vacaville sees daytime highs around 58°F and nights near 42°F. Worth packing: a warm layer and rain gear. About 9 days see rain.

a warm layerrain gear

UV index in Vacaville in December

LowModerateHighVery highExtreme

Clear-sky midday UV in December peaks around 2. 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 December

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where December 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

Location & terrain

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.

2 miles

564 ft

artificial surfaces 47%

10 miles

2,825 ft

grassland 41%

50 miles

4,459 ft

grassland 33%

treesgrasslandcroplandartificial surfacesbare terrainwaterwetland

← November Vacaville year-round climate January →Best places to visit in December

December weather nearby: Fairfield 8.1 mi · Suisun 8.7 mi · Dixon 11 mi · Napa 17 mi · Davis 19 mi · American Canyon 19 mi · Bay Point 22 mi · Vallejo 23 mi

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. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).

	Avg high (°F)	Avg low (°F)
1	60	44
2	60	44
3	60	44
4	59	44
5	59	44
6	59	44
7	59	43
8	58	43
9	58	43
10	58	43
11	58	43
12	58	43
13	58	43
14	57	43
15	57	42
16	57	42
17	57	42
18	57	42
19	57	42
20	57	42
21	57	42
22	56	42
23	56	42
24	56	41
25	56	41
26	56	41
27	56	41
28	56	41
29	56	41
30	56	41
31	56	41

	Clearer (%)	Cloudier (%)
1	51	49
2	49	51
3	49	51
4	48	52
5	47	53
6	46	54
7	45	55
8	45	55
9	44	56
10	44	56
11	44	56
12	44	56
13	44	56
14	44	56
15	45	55
16	45	55
17	45	55
18	46	54
19	46	54
20	47	53
21	47	53
22	46	54
23	46	54
24	46	54
25	46	54
26	45	55
27	44	56
28	44	56
29	44	56
30	44	56
31	43	57

	Rain chance (%)
1	27
2	28
3	28
4	29
5	30
6	30
7	30
8	31
9	31
10	31
11	31
12	31
13	31
14	31
15	30
16	30
17	29
18	29
19	28
20	28
21	28
22	28
23	28
24	28
25	27
26	27
27	27
28	27
29	27
30	27
31	28

	Dry (%)	Comfortable (%)
1	97	3
2	97	3
3	97	3
4	97	3
5	97	3
6	96	4
7	96	4
8	96	4
9	96	4
10	96	4
11	97	3
12	97	3
13	97	3
14	97	3
15	97	3
16	97	3
17	97	3
18	98	2
19	98	2
20	98	2
21	98	2
22	98	2
23	98	2
24	98	2
25	98	2
26	98	2
27	98	2
28	98	2
29	98	2
30	98	2
31	98	2

	Avg high (°F)	Avg low (°F)
1	60	44
2	60	44
3	60	44
4	59	44
5	59	44
6	59	44
7	59	43
8	58	43
9	58	43
10	58	43
11	58	43
12	58	43
13	58	43
14	57	43
15	57	42
16	57	42
17	57	42
18	57	42
19	57	42
20	57	42
21	57	42
22	56	42
23	56	42
24	56	41
25	56	41
26	56	41
27	56	41
28	56	41
29	56	41
30	56	41
31	56	41

	Clearer (%)	Cloudier (%)
1	51	49
2	49	51
3	49	51
4	48	52
5	47	53
6	46	54
7	45	55
8	45	55
9	44	56
10	44	56
11	44	56
12	44	56
13	44	56
14	44	56
15	45	55
16	45	55
17	45	55
18	46	54
19	46	54
20	47	53
21	47	53
22	46	54
23	46	54
24	46	54
25	46	54
26	45	55
27	44	56
28	44	56
29	44	56
30	44	56
31	43	57

	Rain chance (%)
1	27
2	28
3	28
4	29
5	30
6	30
7	30
8	31
9	31
10	31
11	31
12	31
13	31
14	31
15	30
16	30
17	29
18	29
19	28
20	28
21	28
22	28
23	28
24	28
25	27
26	27
27	27
28	27
29	27
30	27
31	28

	Dry (%)	Comfortable (%)
1	97	3
2	97	3
3	97	3
4	97	3
5	97	3
6	96	4
7	96	4
8	96	4
9	96	4
10	96	4
11	97	3
12	97	3
13	97	3
14	97	3
15	97	3
16	97	3
17	97	3
18	98	2
19	98	2
20	98	2
21	98	2
22	98	2
23	98	2
24	98	2
25	98	2
26	98	2
27	98	2
28	98	2
29	98	2
30	98	2
31	98	2

	Avg high (°F)	Avg low (°F)
1	60	44
2	60	44
3	60	44
4	59	44
5	59	44
6	59	44
7	59	43
8	58	43
9	58	43
10	58	43
11	58	43
12	58	43
13	58	43
14	57	43
15	57	42
16	57	42
17	57	42
18	57	42
19	57	42
20	57	42
21	57	42
22	56	42
23	56	42
24	56	41
25	56	41
26	56	41
27	56	41
28	56	41
29	56	41
30	56	41
31	56	41

	Clearer (%)	Cloudier (%)
1	51	49
2	49	51
3	49	51
4	48	52
5	47	53
6	46	54
7	45	55
8	45	55
9	44	56
10	44	56
11	44	56
12	44	56
13	44	56
14	44	56
15	45	55
16	45	55
17	45	55
18	46	54
19	46	54
20	47	53
21	47	53
22	46	54
23	46	54
24	46	54
25	46	54
26	45	55
27	44	56
28	44	56
29	44	56
30	44	56
31	43	57

	Rain chance (%)
1	27
2	28
3	28
4	29
5	30
6	30
7	30
8	31
9	31
10	31
11	31
12	31
13	31
14	31
15	30
16	30
17	29
18	29
19	28
20	28
21	28
22	28
23	28
24	28
25	27
26	27
27	27
28	27
29	27
30	27
31	28

	Dry (%)	Comfortable (%)
1	97	3
2	97	3
3	97	3
4	97	3
5	97	3
6	96	4
7	96	4
8	96	4
9	96	4
10	96	4
11	97	3
12	97	3
13	97	3
14	97	3
15	97	3
16	97	3
17	97	3
18	98	2
19	98	2
20	98	2
21	98	2
22	98	2
23	98	2
24	98	2
25	98	2
26	98	2
27	98	2
28	98	2
29	98	2
30	98	2
31	98	2