Clearlake weather in December

In December, Clearlake sees average daytime highs of 52°F and overnight lows near 38°F, with 6.2 in of precipitation across 10.5 wet days and about 9.3 hours of daylight. It is the 12th-warmest and 1st-wettest month of the year here.

Highs ease over the month, from about 54°F in the first days to 51°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 18 min by month's end. Set against the rest of the year, December is Clearlake's 10th-clearest and 7th-windiest month. For the whole year in context, see Clearlake's year-round climate.

Daytime high: 52°; 12th warmest
Overnight low: 38°; 2nd coldest
Precipitation: 6.2 in; 10.5 wet days
Daylight: 9 h 18 min; 7:28 AM – 4:45 PM
Cloud cover: 60%; 10th clearest
Wind: 4 mph; 7th windiest
Solar energy: 2.01 kWh/m²
Travel score: 2.8; out of 10

Clearlake is city in Lake County, California, United States.

Density: 554/km²; people per km²
Founded: 1980

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

← November Clearlake 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 54°F in the first days to 51°F by the end.

A typical December day in Clearlake reaches about 52°F in the afternoon and slips back to 38°F overnight — a 14°F spread between the day's warmth and the night's chill. On most days the high lands between 45°F and 60°F. Set against its neighbours, December runs about 7°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)	55	54	54	54	54	53	53	53	53	53	53	53	52	52	52	52	52	52	52	51	51	51	51	51	51	51	51	51	51	51	51
Avg low (°F)	40	40	40	40	40	40	39	39	39	39	39	39	39	38	38	38	38	38	38	38	38	38	38	38	37	37	37	37	37	37	37

	Avg high (°F)	Avg low (°F)
1	55	40
2	54	40
3	54	40
4	54	40
5	54	40
6	53	40
7	53	39
8	53	39
9	53	39
10	53	39
11	53	39
12	53	39
13	52	39
14	52	38
15	52	38
16	52	38
17	52	38
18	52	38
19	52	38
20	51	38
21	51	38
22	51	38
23	51	38
24	51	38
25	51	37
26	51	37
27	51	37
28	51	37
29	51	37
30	51	37
31	51	37

Clearlake weather by month

How December compares with the rest of the year at a glance. December is the 12th-warmest and 1st-wettest month here — the current month is highlighted below.

Month	High / Low (°F)	Rainfall (inches)	Wet days	Snow days	Daylight (hours)	Travel score
Jan	53° / 38°	6.1	10.9	1.4	9.6	2.8
Feb	55° / 40°	5.9	9.4	1.7	10.5	3.6
Mar	59° / 42°	4.7	10.4	1.4	11.7	4.6
Apr	64° / 45°	2.1	6.5	0.3	13	6.2
May	71° / 51°	1.4	4.7	0	14.1	7.8
Jun	80° / 58°	0.5	2.1	0	14.7	8.2
Jul	87° / 64°	0.0	0.2	0	14.5	6.6
Aug	86° / 63°	0.1	0.4	0	13.5	6.7
Sep	82° / 59°	0.2	1	0	12.3	8.2
Oct	72° / 52°	1.6	3.8	0	11	8.2
Nov	60° / 43°	3.2	7.1	0.2	9.9	5.1
Dec	52° / 38°	6.2	10.5	0.8	9.3	2.8

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 9% of December, with mostly cloudy or overcast conditions the remaining 57%.

	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 (%)	48	47	47	46	45	44	44	43	42	42	42	41	41	42	43	42	43	43	42	43	43	43	43	43	43	44	43	42	41	41	41
Cloudier (%)	52	53	53	54	55	56	56	57	58	58	58	59	59	58	57	58	57	57	58	57	57	57	57	57	57	56	57	58	59	59	59

	Clearer (%)	Cloudier (%)
1	48	52
2	47	53
3	47	53
4	46	54
5	45	55
6	44	56
7	44	56
8	43	57
9	42	58
10	42	58
11	42	58
12	41	59
13	41	59
14	42	58
15	43	57
16	42	58
17	43	57
18	43	57
19	42	58
20	43	57
21	43	57
22	43	57
23	43	57
24	43	57
25	43	57
26	44	56
27	43	57
28	42	58
29	41	59
30	41	59
31	41	59

Chance of precipitation in December

Any precipitationSnow

Clearlake gets around 6.2 in of rain and snow over 10.5 wet days in December, the wettest month. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 34% and peaks near 36% on the wettest days, and about 1 day brings snow.

	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 (%)	31	32	33	34	34	35	36	36	36	36	36	36	36	36	35	35	34	34	33	33	32	32	32	32	31	31	32	32	32	32	33
Snow chance (%)	1	1	1	1	1	1	1	1	1	1	1	2	2	2	2	2	2	2	3	3	3	4	4	4	4	5	5	5	5	5	6

	Rain chance (%)	Snow chance (%)
1	31	1
2	32	1
3	33	1
4	34	1
5	34	1
6	35	1
7	36	1
8	36	1
9	36	1
10	36	1
11	36	1
12	36	2
13	36	2
14	36	2
15	35	2
16	35	2
17	34	2
18	34	2
19	33	3
20	33	3
21	32	3
22	32	4
23	32	4
24	32	4
25	31	4
26	31	5
27	32	5
28	32	5
29	32	5
30	32	5
31	33	6

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 100% 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 (%)	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100

	Dry (%)
1	100
2	100
3	100
4	100
5	100
6	100
7	100
8	100
9	100
10	100
11	100
12	100
13	100
14	100
15	100
16	100
17	100
18	100
19	100
20	100
21	100
22	100
23	100
24	100
25	100
26	100
27	100
28	100
29	100
30	100
31	100

Wind in December

Winds average 4 mph in December.

Across December, daily wind ranges from about 4 mph on the calmest days to 4 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)	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4
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	4	calm
2	4	calm
3	4	calm
4	4	calm
5	4	calm
6	4	calm
7	4	calm
8	4	calm
9	4	calm
10	4	calm
11	4	calm
12	4	calm
13	4	calm
14	4	calm
15	4	calm
16	4	calm
17	4	calm
18	4	calm
19	4	calm
20	4	calm
21	4	calm
22	4	calm
23	4	calm
24	4	calm
25	4	calm
26	4	calm
27	4	calm
28	4	calm
29	4	calm
30	4	calm
31	4	calm

Sunrise & sunset in December

DaylightNight

Daylight runs from about 9 h 30 min at the start of December to 9 h 18 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 12 minutes over December. Sunrise moves from 7:16 AM to 7:35 AM, and sunset from 4:44 PM to 4:53 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	9.4	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	9.3	9.3	9.3	9.3	9.3	9.3	9.3	9.3
Sunrise (AM)	7:16	7:17	7:18	7:19	7:20	7:21	7:22	7:22	7:23	7:24	7:25	7:26	7:26	7:27	7:28	7:28	7:29	7:29	7:30	7:31	7:31	7:32	7:32	7:32	7:33	7:33	7:34	7:34	7:34	7:34	7:35
Sunset (PM)	4:44	4:44	4:44	4:44	4:44	4:44	4:44	4:44	4:44	4:44	4:44	4:44	4:44	4:45	4:45	4:45	4:45	4:46	4:46	4:47	4:47	4:47	4:48	4:48	4:49	4:49	4:50	4:51	4:51	4:52	4:53

	Daylight (h)	Sunrise (AM)	Sunset (PM)
1	9.5	7:16	4:44
2	9.4	7:17	4:44
3	9.4	7:18	4:44
4	9.4	7:19	4:44
5	9.4	7:20	4:44
6	9.4	7:21	4:44
7	9.4	7:22	4:44
8	9.4	7:22	4:44
9	9.3	7:23	4:44
10	9.3	7:24	4:44
11	9.3	7:25	4:44
12	9.3	7:26	4:44
13	9.3	7:26	4:44
14	9.3	7:27	4:45
15	9.3	7:28	4:45
16	9.3	7:28	4:45
17	9.3	7:29	4:45
18	9.3	7:29	4:46
19	9.3	7:30	4:46
20	9.3	7:31	4:47
21	9.3	7:31	4:47
22	9.3	7:32	4:47
23	9.3	7:32	4:48
24	9.3	7:32	4:48
25	9.3	7:33	4:49
26	9.3	7:33	4:49
27	9.3	7:34	4:50
28	9.3	7:34	4:51
29	9.3	7:34	4:51
30	9.3	7:34	4:52
31	9.3	7:35	4:53

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 2.01 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 2.01 kWh/m² to a high of 8.26 kWh/m² in July across the year — December's 2.01 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	2.1	2.1	2.1	2.1	2.0	2.0	2.0	2.0	2.0	2.0	1.9	1.9	1.9	1.9	1.9	1.9	1.9	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0
Level	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate

	Solar energy (kWh/m²)	Level
1	2.2	Moderate
2	2.1	Moderate
3	2.1	Moderate
4	2.1	Moderate
5	2.1	Moderate
6	2.0	Moderate
7	2.0	Moderate
8	2.0	Moderate
9	2.0	Dim
10	2.0	Dim
11	2.0	Dim
12	1.9	Dim
13	1.9	Dim
14	1.9	Dim
15	1.9	Dim
16	1.9	Dim
17	1.9	Dim
18	1.9	Dim
19	2.0	Dim
20	2.0	Dim
21	2.0	Dim
22	2.0	Dim
23	2.0	Dim
24	2.0	Moderate
25	2.0	Moderate
26	2.0	Moderate
27	2.0	Moderate
28	2.0	Moderate
29	2.0	Moderate
30	2.0	Moderate
31	2.0	Moderate

Planning a trip in December

Hazard calendar for Clearlake

In seasonPeak

In December, Clearlake sits inside its rainy season season. The full year is below, with each hazard's peak months called out.

Clearlake'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 Clearlake?

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

2.8

Sightseeing

11th-best month of the year

0.0

Beach & pool

11th-best month of the year

December is a weaker month for outdoor sightseeing in Clearlake.

What to pack for Clearlake in December

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

In December, Clearlake sees daytime highs around 52°F and nights near 38°F. Pack a warm layer. Worth having: rain gear. About 11 days see rain.

a warm layerrain gear

UV index in Clearlake 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 Clearlake peaks around June 23 at about 10 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 15 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	3	5	6	9	10	10	9	6	5	2	2
Level	Moderate	Moderate	Moderate	High	Very high	Extreme	Extreme	Very high	High	High	Moderate	Low

	UV index (midday)	Level
Jan	2	Moderate
Feb	3	Moderate
Mar	5	Moderate
Apr	6	High
May	9	Very high
Jun	10	Extreme
Jul	10	Extreme
Aug	9	Very high
Sep	6	High
Oct	5	High
Nov	2	Moderate
Dec	2	Low

Air quality in Clearlake 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 Clearlake is worst in September — around 31 µg/m³ PM2.5 (moderate), about 5.8× the cleanest month (June, 5 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)	6	8	9	8	6	5	14	29	31	14	8	6
Level	Good	Good	Good	Good	Good	Good	Moderate	Moderate	Moderate	Moderate	Good	Good

	PM2.5 (µg/m³)	Level
Jan	6	Good
Feb	8	Good
Mar	9	Good
Apr	8	Good
May	6	Good
Jun	5	Good
Jul	14	Moderate
Aug	29	Moderate
Sep	31	Moderate
Oct	14	Moderate
Nov	8	Good
Dec	6	Good

Location & terrain

Where is Clearlake?

Clearlake sits at 39.0°N, 122.6°W, 1,417 ft above sea level, in United States. The nearest listed city is Windsor, 30 mi away.

Topography around Clearlake

How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Clearlake.

Within 2 miles, the terrain around Clearlake has significant variations in elevation — a maximum elevation change of 853 ft around an average of 1,493 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 3,409 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 6,982 ft.

The land around Clearlake is covered by trees (39%) and grassland (28%) within 2 miles, trees (52%) and grassland (38%) within 10 miles, and trees (52%) and grassland (30%) within 50 miles.

2 miles

853 ft

trees 39%

10 miles

3,409 ft

trees 52%

50 miles

6,982 ft

trees 52%

treesgrasslandcroplandartificial surfaceswater

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

December weather nearby: Windsor 30 mi · Ukiah 34 mi · Santa Rosa 36 mi · Rohnert Park 43 mi · Agua Caliente 45 mi · Napa 49 mi · Woodland 50 mi · Petaluma 50 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 Clearlake (38.9582°, -122.6264°, elevation 1,417 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	55	40
2	54	40
3	54	40
4	54	40
5	54	40
6	53	40
7	53	39
8	53	39
9	53	39
10	53	39
11	53	39
12	53	39
13	52	39
14	52	38
15	52	38
16	52	38
17	52	38
18	52	38
19	52	38
20	51	38
21	51	38
22	51	38
23	51	38
24	51	38
25	51	37
26	51	37
27	51	37
28	51	37
29	51	37
30	51	37
31	51	37

	Clearer (%)	Cloudier (%)
1	48	52
2	47	53
3	47	53
4	46	54
5	45	55
6	44	56
7	44	56
8	43	57
9	42	58
10	42	58
11	42	58
12	41	59
13	41	59
14	42	58
15	43	57
16	42	58
17	43	57
18	43	57
19	42	58
20	43	57
21	43	57
22	43	57
23	43	57
24	43	57
25	43	57
26	44	56
27	43	57
28	42	58
29	41	59
30	41	59
31	41	59

	Rain chance (%)	Snow chance (%)
1	31	1
2	32	1
3	33	1
4	34	1
5	34	1
6	35	1
7	36	1
8	36	1
9	36	1
10	36	1
11	36	1
12	36	2
13	36	2
14	36	2
15	35	2
16	35	2
17	34	2
18	34	2
19	33	3
20	33	3
21	32	3
22	32	4
23	32	4
24	32	4
25	31	4
26	31	5
27	32	5
28	32	5
29	32	5
30	32	5
31	33	6

	Dry (%)
1	100
2	100
3	100
4	100
5	100
6	100
7	100
8	100
9	100
10	100
11	100
12	100
13	100
14	100
15	100
16	100
17	100
18	100
19	100
20	100
21	100
22	100
23	100
24	100
25	100
26	100
27	100
28	100
29	100
30	100
31	100

	Avg high (°F)	Avg low (°F)
1	55	40
2	54	40
3	54	40
4	54	40
5	54	40
6	53	40
7	53	39
8	53	39
9	53	39
10	53	39
11	53	39
12	53	39
13	52	39
14	52	38
15	52	38
16	52	38
17	52	38
18	52	38
19	52	38
20	51	38
21	51	38
22	51	38
23	51	38
24	51	38
25	51	37
26	51	37
27	51	37
28	51	37
29	51	37
30	51	37
31	51	37

	Clearer (%)	Cloudier (%)
1	48	52
2	47	53
3	47	53
4	46	54
5	45	55
6	44	56
7	44	56
8	43	57
9	42	58
10	42	58
11	42	58
12	41	59
13	41	59
14	42	58
15	43	57
16	42	58
17	43	57
18	43	57
19	42	58
20	43	57
21	43	57
22	43	57
23	43	57
24	43	57
25	43	57
26	44	56
27	43	57
28	42	58
29	41	59
30	41	59
31	41	59

	Rain chance (%)	Snow chance (%)
1	31	1
2	32	1
3	33	1
4	34	1
5	34	1
6	35	1
7	36	1
8	36	1
9	36	1
10	36	1
11	36	1
12	36	2
13	36	2
14	36	2
15	35	2
16	35	2
17	34	2
18	34	2
19	33	3
20	33	3
21	32	3
22	32	4
23	32	4
24	32	4
25	31	4
26	31	5
27	32	5
28	32	5
29	32	5
30	32	5
31	33	6

	Dry (%)
1	100
2	100
3	100
4	100
5	100
6	100
7	100
8	100
9	100
10	100
11	100
12	100
13	100
14	100
15	100
16	100
17	100
18	100
19	100
20	100
21	100
22	100
23	100
24	100
25	100
26	100
27	100
28	100
29	100
30	100
31	100

	Avg high (°F)	Avg low (°F)
1	55	40
2	54	40
3	54	40
4	54	40
5	54	40
6	53	40
7	53	39
8	53	39
9	53	39
10	53	39
11	53	39
12	53	39
13	52	39
14	52	38
15	52	38
16	52	38
17	52	38
18	52	38
19	52	38
20	51	38
21	51	38
22	51	38
23	51	38
24	51	38
25	51	37
26	51	37
27	51	37
28	51	37
29	51	37
30	51	37
31	51	37

	Clearer (%)	Cloudier (%)
1	48	52
2	47	53
3	47	53
4	46	54
5	45	55
6	44	56
7	44	56
8	43	57
9	42	58
10	42	58
11	42	58
12	41	59
13	41	59
14	42	58
15	43	57
16	42	58
17	43	57
18	43	57
19	42	58
20	43	57
21	43	57
22	43	57
23	43	57
24	43	57
25	43	57
26	44	56
27	43	57
28	42	58
29	41	59
30	41	59
31	41	59

	Rain chance (%)	Snow chance (%)
1	31	1
2	32	1
3	33	1
4	34	1
5	34	1
6	35	1
7	36	1
8	36	1
9	36	1
10	36	1
11	36	1
12	36	2
13	36	2
14	36	2
15	35	2
16	35	2
17	34	2
18	34	2
19	33	3
20	33	3
21	32	3
22	32	4
23	32	4
24	32	4
25	31	4
26	31	5
27	32	5
28	32	5
29	32	5
30	32	5
31	33	6

	Dry (%)
1	100
2	100
3	100
4	100
5	100
6	100
7	100
8	100
9	100
10	100
11	100
12	100
13	100
14	100
15	100
16	100
17	100
18	100
19	100
20	100
21	100
22	100
23	100
24	100
25	100
26	100
27	100
28	100
29	100
30	100
31	100