Caldwell weather in December

In December, Caldwell sees average daytime highs of 40°F and overnight lows near 27°F, with 1.7 in of precipitation across 9.3 wet days and about 8.8 hours of daylight. It is the 12th-warmest and 1st-wettest month of the year here.

Highs ease over the month, from about 43°F in the first days to 39°F by the end. The sky is clear or mostly clear about 27% of the time in December, and the air most often feels dry.

Daylight stretches from about 9 hours at the start of December to 8 h 48 min by month's end. Set against the rest of the year, December is Caldwell's 11th-clearest and 7th-windiest month. For the whole year in context, see Caldwell's year-round climate.

Daytime high
40°
12th warmest
Overnight low
27°
2nd coldest
Precipitation
1.7 in
9.3 wet days
Daylight
8 h 48 min
8:20 AM – 5:06 PM
Cloud cover
63%
11th clearest
Wind
5 mph
7th windiest
Solar energy
1.59 kWh/m²
Travel score
0.1
out of 10

Caldwell is city in and county seat of Canyon County, Idaho, United States.

Density
898/km²
people per km²
Founded
1883

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

Temperature in December

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 43°F in the first days to 39°F by the end.

A typical December day in Caldwell reaches about 40°F in the afternoon and slips back to 27°F overnight — a 13°F spread between the day's warmth and the night's chill. On most days the high lands between 30°F and 50°F. Set against its neighbours, December runs about 10°F cooler than November and on par with January.

20°30°40°50°60°151015202531
Avg high (°F)Avg low (°F)
14329
24329
34329
44229
54229
64228
74228
84128
94128
104128
114128
124128
134028
144028
154028
164027
174027
184027
194027
204027
213927
223927
233927
243926
253926
263926
273926
283926
293926
303926
313926

How December really feels in Caldwell

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
0
heat index over the day's high
Days feeling ≤ 32°F
31
wind chill below the day's low

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

Caldwell 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.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan41° / 27°1.58.73.79.10.1
Feb48° / 30°1.072.110.21.7
Mar58° / 37°1.280.511.64.4
Apr65° / 42°1.06.20.113.26.4
May75° / 50°1.05.7014.57.6
Jun83° / 57°0.53.1015.26.8
Jul94° / 64°0.10.7014.93.7
Aug92° / 62°0.10.9013.84.3
Sep81° / 54°0.42012.37.7
Oct66° / 43°0.74010.87.1
Nov50° / 34°1.17.419.52.5
Dec40° / 27°1.79.33.58.80.1

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 27% 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 59%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14555
24456
34456
44456
54357
64357
74258
84258
94258
104159
114159
124060
134060
144060
153961
163961
173961
184060
194060
204159
214159
224159
234159
244159
254159
264159
274159
283961
294060
304060
313961

Chance of precipitation in December

Any precipitationSnow

Caldwell gets around 1.7 in of rain and snow over 9.3 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 29% and peaks near 30% on the wettest days, and about 4 days bring snow.

0%10%20%30%40%151015202531
Rain chance (%)Snow chance (%)
1299
22910
32910
42910
52910
62910
72910
82910
92910
102910
112910
122910
132910
142910
152910
162910
172910
182911
192911
202911
212911
223012
233012
243012
253012
263012
273012
282912
292913
302913
312913

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.

0%25%50%75%100%151015202531
Dry (%)
1100
2100
3100
4100
5100
6100
7100
8100
9100
10100
11100
12100
13100
14100
15100
16100
17100
18100
19100
20100
21100
22100
23100
24100
25100
26100
27100
28100
29100
30100
31100

Wind in December

Winds average 5 mph in December.

Across December, daily wind ranges from about 4 mph on the calmest days to 5 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (mph)Feels
15calm
25calm
35calm
45calm
55calm
65calm
75calm
85calm
95calm
105calm
115calm
125calm
135calm
145calm
155calm
165calm
175calm
185calm
195calm
205calm
215calm
225calm
235calm
245calm
255calm
265calm
274calm
284calm
294calm
304calm
314calm

Sunrise & sunset in December

DaylightNight

Daylight runs from about 9 hours at the start of December to 8 h 48 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 8:07 AM to 8:26 AM, and sunset from 5:06 PM to 5:14 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
19.08:075:06
29.08:085:06
38.98:095:06
48.98:105:05
58.98:115:05
68.98:125:05
78.98:135:05
88.98:145:05
98.88:155:05
108.88:165:05
118.88:165:05
128.88:175:05
138.88:185:05
148.88:195:05
158.88:195:06
168.88:205:06
178.88:215:06
188.88:215:06
198.78:225:07
208.78:225:07
218.78:235:07
228.78:235:08
238.78:245:08
248.78:245:09
258.78:255:10
268.88:255:10
278.88:255:11
288.88:265:11
298.88:265:12
308.88:265:13
318.88:265:14

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 1.59 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 1.59 kWh/m² to a high of 8.01 kWh/m² in July across the year — December's 1.59 kWh/m² sits near the bottom.

00.511.522.5151015202531
Solar energy (kWh/m²)Level
11.7Dim
21.7Dim
31.7Dim
41.6Dim
51.6Dim
61.6Dim
71.6Dim
81.6Dim
91.6Dim
101.6Dim
111.6Dim
121.6Dim
131.6Dim
141.6Dim
151.6Dim
161.6Dim
171.6Dim
181.6Dim
191.6Dim
201.6Dim
211.6Dim
221.6Dim
231.6Dim
241.6Dim
251.6Dim
261.6Dim
271.6Dim
281.6Dim
291.6Dim
301.6Dim
311.6Dim
Planning a trip in December

Is December a good time to visit Caldwell?

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

0.1
Sightseeing
11th-best month of the year
0.0
Beach & pool
10th-best month of the year

December is a weaker month for outdoor sightseeing in Caldwell.

What to pack for Caldwell in December

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

In December, Caldwell sees daytime highs around 40°F and nights near 27°F. Pack a warm layer. Worth having: a heavy coat and rain gear. About 9 days see rain.

a warm layera heavy coatrain gear

UV index in Caldwell in December

LowModerateHighVery highExtreme

Clear-sky midday UV in December peaks around 1. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Caldwell peaks around July 13 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 14 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJul 13UV 9Dec 14UV 1
UV index (midday)Level
Jan2Low
Feb2Moderate
Mar4Moderate
Apr5High
May8Very high
Jun8Very high
Jul9Very high
Aug7Very high
Sep6High
Oct4Moderate
Nov2Low
Dec1Low

Air quality in Caldwell 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 Caldwell is worst in August — around 31 µg/m³ PM2.5 (moderate), about 5.0× the cleanest month (December, 6 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

010203040JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodAug 1729 µg/m³Dec 206 µg/m³
PM2.5 (µg/m³)Level
Jan7Good
Feb8Good
Mar10Good
Apr9Good
May10Good
Jun8Good
Jul15Moderate
Aug31Moderate
Sep16Moderate
Oct11Good
Nov8Good
Dec6Good
Location & terrain

Where is Caldwell?

Caldwell sits at 43.7°N, 116.7°W, 2,375 ft above sea level, in United States. The nearest listed city is Nampa, 11 mi away.

Topography around Caldwell

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

Within 2 miles, the terrain around Caldwell has only modest variations in elevation — a maximum elevation change of 141 ft around an average of 2,385 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 620 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 6,283 ft.

The land around Caldwell is covered by artificial surfaces (37%) within 2 miles, cropland (48%) and grassland (21%) within 10 miles, and grassland (70%) within 50 miles.

2 miles
141 ft
10 miles
620 ft
50 miles
6,283 ft
treesshrubsgrasslandcroplandartificial surfacesbare terrainwater
December weather nearby: Nampa 11 mi · Meridian 15 mi · Eagle 17 mi · Kuna 18 mi · Boise 24 mi · Twin Falls 135 mi · Pendleton 173 mi · Walla Walla 185 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
Protestant 47%unaffiliated 23%Roman Catholic 21%Jewish 2%

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 Caldwell (43.6629°, -116.6874°, elevation 2,375 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).