Castle Rock weather in December

In December, Castle Rock sees average daytime highs of 39°F and overnight lows near 12°F, with 0.7 in of precipitation across 3.9 wet days and about 9.3 hours of daylight. It is the 12th-warmest and 11th-wettest month of the year here.

Highs ease over the month, from about 41°F in the first days to 38°F by the end. The sky is clear or mostly clear about 56% of the time in December, and the air most often feels dry.

Daylight stretches from about 9 h 24 min at the start of December to 9 h 18 min by month's end. Set against the rest of the year, December is Castle Rock's 3rd-clearest and 7th-windiest month. For the whole year in context, see Castle Rock's year-round climate.

Daytime high: 39°; 12th warmest
Overnight low: 12°; 2nd coldest
Precipitation: 0.7 in; 3.9 wet days
Daylight: 9 h 12 min; 7:18 AM – 4:33 PM
Cloud cover: 39%; 3rd clearest
Wind: 5 mph; 7th windiest
Solar energy: 2.61 kWh/m²
Travel score: 0.0; out of 10

Castle Rock is town in and seat of Douglas County, Colorado, United States.

Density: 635/km²; people per km²
Founded: 1874

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

← November Castle Rock 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 41°F in the first days to 38°F by the end.

A typical December day in Castle Rock reaches about 39°F in the afternoon and slips back to 12°F overnight — a 26°F spread between the day's warmth and the night's chill. On most days the high lands between 24°F and 53°F. Set against its neighbours, December runs about 9°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)	42	41	41	41	41	40	40	40	40	40	39	39	39	39	39	38	38	38	38	38	38	38	38	38	38	38	38	38	38	38	38
Avg low (°F)	16	15	15	15	14	14	14	14	13	13	13	13	12	12	12	12	12	11	11	11	11	11	11	11	11	11	11	11	11	11	11

	Avg high (°F)	Avg low (°F)
1	42	16
2	41	15
3	41	15
4	41	15
5	41	14
6	40	14
7	40	14
8	40	14
9	40	13
10	40	13
11	39	13
12	39	13
13	39	12
14	39	12
15	39	12
16	38	12
17	38	12
18	38	11
19	38	11
20	38	11
21	38	11
22	38	11
23	38	11
24	38	11
25	38	11
26	38	11
27	38	11
28	38	11
29	38	11
30	38	11
31	38	11

How December really feels in Castle Rock

Once humidity and wind are folded in, December averages 0 days that feel above 90°F and 31 that feel at or below 32°F — the comfort signal a plain temperature reading hides.

Days feeling ≥ 90°F

heat index over the day's high

Days feeling ≤ 32°F

31 feel bitter (≤ 14°F)

The story in December is cold — wind chill drags the overnight "feels like" below the raw low.

Castle Rock weather by month

How December compares with the rest of the year at a glance. December is the 12th-warmest and 11th-wettest month here — the current month is highlighted below.

Month	High / Low (°F)	Rainfall (inches)	Wet days	Snow days	Daylight (hours)	Travel score
Jan	39° / 12°	0.6	4.2	4.7	9.5	0.0
Feb	42° / 15°	0.7	5	5.4	10.5	0.3
Mar	49° / 22°	1.7	6.9	5.9	11.7	2.2
Apr	55° / 28°	2.6	9.7	6.1	13	3.5
May	65° / 39°	3.0	12.3	1.7	14.1	5.5
Jun	76° / 48°	2.1	10.2	0.1	14.7	6.8
Jul	81° / 54°	2.5	10.9	0	14.5	6.5
Aug	79° / 52°	2.0	10.1	0	13.5	6.9
Sep	72° / 45°	1.3	6.4	0.5	12.3	7.6
Oct	60° / 32°	1.4	5.5	2.4	11	5.7
Nov	48° / 21°	1.0	4.9	4.9	9.8	2.0
Dec	39° / 12°	0.7	3.9	4.4	9.3	0.0

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 56% of the time in December.

Beyond those clear spells, partly cloudy skies cover about 14% of December, with mostly cloudy or overcast conditions the remaining 30%.

	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 (%)	69	69	69	69	70	70	70	70	70	71	70	70	70	70	70	71	71	71	71	71	71	71	71	71	71	70	70	71	71	70	70
Cloudier (%)	31	31	31	31	30	30	30	30	30	29	30	30	30	30	30	29	29	29	29	29	29	29	29	29	29	30	30	29	29	30	30

	Clearer (%)	Cloudier (%)
1	69	31
2	69	31
3	69	31
4	69	31
5	70	30
6	70	30
7	70	30
8	70	30
9	70	30
10	71	29
11	70	30
12	70	30
13	70	30
14	70	30
15	70	30
16	71	29
17	71	29
18	71	29
19	71	29
20	71	29
21	71	29
22	71	29
23	71	29
24	71	29
25	71	29
26	70	30
27	70	30
28	71	29
29	71	29
30	70	30
31	70	30

Chance of precipitation in December

Any precipitationSnow

Castle Rock gets around 0.7 in of rain and snow over 3.9 wet days in December. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 13% and peaks near 15% on the wettest days, and about 4 days bring 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 (%)	15	15	14	14	14	14	13	13	13	13	13	13	13	13	13	14	14	14	14	14	13	13	13	13	13	13	13	13	13	13	13
Snow chance (%)	16	16	15	15	15	15	15	14	14	14	14	14	14	15	15	15	15	15	15	15	15	15	15	15	15	15	15	15	15	15	15

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

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 5 mph in December.

Across December, daily wind ranges from about 5 mph on the calmest days to 6 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)	6	6	6	6	6	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	6	calm
2	6	calm
3	6	calm
4	6	calm
5	6	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 24 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 6 minutes over December. Sunrise moves from 7:06 AM to 7:25 AM, and sunset from 4:32 PM to 4:40 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)	9.4	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	9.2	9.2	9.2	9.2	9.2	9.2	9.2	9.2	9.2	9.2	9.2	9.2	9.2	9.2	9.2	9.3	9.3
Sunrise (AM)	7:06	7:07	7:08	7:09	7:10	7:11	7:12	7:13	7:13	7:14	7:15	7:16	7:16	7:17	7:18	7:18	7:19	7:20	7:20	7:21	7:21	7:22	7:22	7:23	7:23	7:23	7:24	7:24	7:24	7:25	7:25
Sunset (PM)	4:32	4:32	4:32	4:32	4:31	4:31	4:31	4:31	4:31	4:32	4:32	4:32	4:32	4:32	4:32	4:33	4:33	4:33	4:34	4:34	4:35	4:35	4:36	4:36	4:37	4:37	4:38	4:38	4:39	4:40	4:40

	Daylight (h)	Sunrise (AM)	Sunset (PM)
1	9.4	7:06	4:32
2	9.4	7:07	4:32
3	9.4	7:08	4:32
4	9.4	7:09	4:32
5	9.4	7:10	4:31
6	9.3	7:11	4:31
7	9.3	7:12	4:31
8	9.3	7:13	4:31
9	9.3	7:13	4:31
10	9.3	7:14	4:32
11	9.3	7:15	4:32
12	9.3	7:16	4:32
13	9.3	7:16	4:32
14	9.3	7:17	4:32
15	9.2	7:18	4:32
16	9.2	7:18	4:33
17	9.2	7:19	4:33
18	9.2	7:20	4:33
19	9.2	7:20	4:34
20	9.2	7:21	4:34
21	9.2	7:21	4:35
22	9.2	7:22	4:35
23	9.2	7:22	4:36
24	9.2	7:23	4:36
25	9.2	7:23	4:37
26	9.2	7:23	4:37
27	9.2	7:24	4:38
28	9.2	7:24	4:38
29	9.2	7:24	4:39
30	9.3	7:25	4:40
31	9.3	7:25	4:40

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 2.61 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 2.61 kWh/m² to a high of 7.41 kWh/m² in June across the year — December's 2.61 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)	2.7	2.7	2.7	2.7	2.6	2.6	2.6	2.6	2.6	2.6	2.6	2.6	2.6	2.6	2.6	2.6	2.6	2.6	2.6	2.6	2.6	2.6	2.6	2.6	2.6	2.6	2.6	2.7	2.7	2.7	2.7
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	2.7	Moderate
2	2.7	Moderate
3	2.7	Moderate
4	2.7	Moderate
5	2.6	Moderate
6	2.6	Moderate
7	2.6	Moderate
8	2.6	Moderate
9	2.6	Moderate
10	2.6	Moderate
11	2.6	Moderate
12	2.6	Moderate
13	2.6	Moderate
14	2.6	Moderate
15	2.6	Moderate
16	2.6	Moderate
17	2.6	Moderate
18	2.6	Moderate
19	2.6	Moderate
20	2.6	Moderate
21	2.6	Moderate
22	2.6	Moderate
23	2.6	Moderate
24	2.6	Moderate
25	2.6	Moderate
26	2.6	Moderate
27	2.6	Moderate
28	2.7	Moderate
29	2.7	Moderate
30	2.7	Moderate
31	2.7	Moderate

Planning a trip in December

Is December a good time to visit Castle Rock?

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

0.0

Sightseeing

11th-best month of the year

0.0

Beach & pool

9th-best month of the year

December is a weaker month for outdoor sightseeing in Castle Rock.

What to pack for Castle Rock in December

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

In December, Castle Rock sees daytime highs around 39°F and nights near 12°F. Pack a warm layer and a heavy coat. About 4 days see rain.

a warm layera heavy coat

UV index in Castle Rock 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 Castle Rock peaks around July 15 at about 11 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 22 at about 2 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 10 months of the year.

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
UV index (midday)	3	4	7	7	8	11	11	10	8	6	4	2
Level	Moderate	Moderate	Very high	High	Very high	Extreme	Extreme	Extreme	Very high	High	Moderate	Moderate

	UV index (midday)	Level
Jan	3	Moderate
Feb	4	Moderate
Mar	7	Very high
Apr	7	High
May	8	Very high
Jun	11	Extreme
Jul	11	Extreme
Aug	10	Extreme
Sep	8	Very high
Oct	6	High
Nov	4	Moderate
Dec	2	Moderate

Location & terrain

Where is Castle Rock?

Castle Rock sits at 39.4°N, 104.9°W, 6,224 ft above sea level, in United States. The nearest listed city is Parker, 11 mi away.

Topography around Castle Rock

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

Within 2 miles, the terrain around Castle Rock has only modest variations in elevation — a maximum elevation change of 646 ft around an average of 6,368 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 2,028 ft; within 50 miles, extreme variations in elevation — a maximum elevation change of 9,268 ft.

The land around Castle Rock is covered by grassland (52%) and artificial surfaces (28%) within 2 miles, grassland (74%) within 10 miles, and grassland (55%) and trees (29%) within 50 miles.

2 miles

646 ft

grassland 52%

10 miles

2,028 ft

grassland 74%

50 miles

9,268 ft

grassland 55%

treesgrasslandcroplandartificial surfacesbare terrainwater

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

December weather nearby: Parker 11 mi · Highlands Ranch 14 mi · Centennial 14 mi · Castlewood 15 mi · Southglenn 16 mi · Greenwood Village 17 mi · Littleton 19 mi · Columbine 19 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 Castle Rock (39.3722°, -104.8561°, elevation 6,224 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. 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	42	16
2	41	15
3	41	15
4	41	15
5	41	14
6	40	14
7	40	14
8	40	14
9	40	13
10	40	13
11	39	13
12	39	13
13	39	12
14	39	12
15	39	12
16	38	12
17	38	12
18	38	11
19	38	11
20	38	11
21	38	11
22	38	11
23	38	11
24	38	11
25	38	11
26	38	11
27	38	11
28	38	11
29	38	11
30	38	11
31	38	11

	Clearer (%)	Cloudier (%)
1	69	31
2	69	31
3	69	31
4	69	31
5	70	30
6	70	30
7	70	30
8	70	30
9	70	30
10	71	29
11	70	30
12	70	30
13	70	30
14	70	30
15	70	30
16	71	29
17	71	29
18	71	29
19	71	29
20	71	29
21	71	29
22	71	29
23	71	29
24	71	29
25	71	29
26	70	30
27	70	30
28	71	29
29	71	29
30	70	30
31	70	30

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

	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	42	16
2	41	15
3	41	15
4	41	15
5	41	14
6	40	14
7	40	14
8	40	14
9	40	13
10	40	13
11	39	13
12	39	13
13	39	12
14	39	12
15	39	12
16	38	12
17	38	12
18	38	11
19	38	11
20	38	11
21	38	11
22	38	11
23	38	11
24	38	11
25	38	11
26	38	11
27	38	11
28	38	11
29	38	11
30	38	11
31	38	11

	Clearer (%)	Cloudier (%)
1	69	31
2	69	31
3	69	31
4	69	31
5	70	30
6	70	30
7	70	30
8	70	30
9	70	30
10	71	29
11	70	30
12	70	30
13	70	30
14	70	30
15	70	30
16	71	29
17	71	29
18	71	29
19	71	29
20	71	29
21	71	29
22	71	29
23	71	29
24	71	29
25	71	29
26	70	30
27	70	30
28	71	29
29	71	29
30	70	30
31	70	30

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

	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	42	16
2	41	15
3	41	15
4	41	15
5	41	14
6	40	14
7	40	14
8	40	14
9	40	13
10	40	13
11	39	13
12	39	13
13	39	12
14	39	12
15	39	12
16	38	12
17	38	12
18	38	11
19	38	11
20	38	11
21	38	11
22	38	11
23	38	11
24	38	11
25	38	11
26	38	11
27	38	11
28	38	11
29	38	11
30	38	11
31	38	11

	Clearer (%)	Cloudier (%)
1	69	31
2	69	31
3	69	31
4	69	31
5	70	30
6	70	30
7	70	30
8	70	30
9	70	30
10	71	29
11	70	30
12	70	30
13	70	30
14	70	30
15	70	30
16	71	29
17	71	29
18	71	29
19	71	29
20	71	29
21	71	29
22	71	29
23	71	29
24	71	29
25	71	29
26	70	30
27	70	30
28	71	29
29	71	29
30	70	30
31	70	30

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

	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