Boise weather in December

In December, Boise sees average daytime highs of 39°F and overnight lows near 27°F, with 2.0 in of precipitation across 10.1 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 42°F in the first days to 38°F by the end. The sky is clear or mostly clear about 28% 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 Boise's 11th-clearest and 3rd-windiest month. For the whole year in context, see Boise's year-round climate.

Daytime high
39°
12th warmest
Overnight low
27°
2nd coldest
Precipitation
2.0 in
10.1 wet days
Daylight
8 h 48 min
8:18 AM – 5:04 PM
Cloud cover
62%
11th clearest
Wind
7 mph
3rd windiest
Solar energy
1.66 kWh/m²
Travel score
0.0
out of 10

Boise is capital city of the U.S. state of Idaho and seat of Ada County.

Density
1/km²
people per km²
Founded
1863

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 42°F in the first days to 38°F by the end.

A typical December day in Boise reaches about 39°F in the afternoon and slips back to 27°F overnight — a 12°F spread between the day's warmth and the night's chill. On most days the high lands between 30°F and 49°F. Set against its neighbours, December runs about 10°F cooler than November and on par with January.

20°40°60°151015202531
Avg high (°F)Avg low (°F)
14229
24229
34229
44128
54128
64128
74028
84028
94028
104028
114028
124028
134028
143927
153927
163927
173927
183927
193927
203927
213826
223826
233826
243826
253826
263826
273826
283826
293826
303826
313826

How December really feels in Boise

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.

Boise 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
Jan40° / 27°1.89.54.89.10.0
Feb46° / 30°1.27.7310.21.2
Mar55° / 36°1.48.91.111.63.7
Apr63° / 41°1.27.20.313.25.8
May72° / 48°1.25.90.114.57.5
Jun81° / 55°0.63.2015.27.4
Jul92° / 63°0.10.9014.94.4
Aug91° / 62°0.10.7013.84.9
Sep80° / 54°0.42.2012.38.1
Oct65° / 43°0.94.30.110.86.8
Nov49° / 33°1.47.929.52.2
Dec39° / 27°2.010.15.28.80.0

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 28% 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 58%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14456
24456
34357
44357
54357
64357
74258
84258
94258
104159
114159
124159
134060
144159
154159
164159
174159
184258
194258
204258
214357
224357
234258
244258
254258
264258
274159
284159
294159
304159
314060

Chance of precipitation in December

Any precipitationSnow

Boise gets around 2.0 in of rain and snow over 10.1 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 32% and peaks near 33% on the wettest days, and about 5 days bring snow.

0%10%20%30%40%151015202531
Rain chance (%)Snow chance (%)
13214
23214
33214
43214
53214
63314
73314
83314
93314
103314
113214
123215
133215
143215
153215
163216
173216
183217
193217
203218
213218
223218
233219
243219
253219
263219
273119
283119
293118
303118
313118

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 7 mph in December.

Across December, daily wind ranges from about 7 mph on the calmest days to 7 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (mph)Feels
17calm
27calm
37calm
47calm
57calm
67calm
77calm
87calm
97calm
107calm
117calm
127calm
137calm
147calm
157calm
167calm
177calm
187calm
197calm
207calm
217calm
227calm
237calm
247calm
257calm
267calm
277calm
287calm
297calm
307calm
317calm

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 8:05 AM to 8:24 AM, and sunset from 5:04 PM to 5:12 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
19.08:055:04
29.08:065:04
38.98:075:04
48.98:085:04
58.98:095:03
68.98:105:03
78.98:115:03
88.98:125:03
98.88:135:03
108.88:135:03
118.88:145:03
128.88:155:03
138.88:165:03
148.88:175:04
158.88:175:04
168.88:185:04
178.88:195:04
188.88:195:05
198.88:205:05
208.78:205:05
218.78:215:06
228.78:215:06
238.78:225:07
248.78:225:07
258.88:235:08
268.88:235:08
278.88:235:09
288.88:245:10
298.88:245:10
308.88:245:11
318.88:245:12

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 1.66 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 1.66 kWh/m² to a high of 8.03 kWh/m² in July across the year — December's 1.66 kWh/m² sits near the bottom.

00.511.522.5151015202531
Solar energy (kWh/m²)Level
11.8Dim
21.8Dim
31.7Dim
41.7Dim
51.7Dim
61.7Dim
71.7Dim
81.7Dim
91.7Dim
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
241.7Dim
251.7Dim
261.7Dim
271.7Dim
281.7Dim
291.7Dim
301.7Dim
311.7Dim
Planning a trip in December

Is December a good time to visit Boise?

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
10th-best month of the year

December is a weaker month for outdoor sightseeing in Boise.

What to pack for Boise in December

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

In December, Boise sees daytime highs around 39°F and nights near 27°F. Pack a warm layer and a heavy coat. Worth having: rain gear. About 10 days see rain.

a warm layera heavy coatrain gear

UV index in Boise 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 Boise 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
Jun9Very high
Jul9Very high
Aug7Very high
Sep6High
Oct4Moderate
Nov2Low
Dec1Low

Air quality in Boise 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 Boise is worst in August — around 45 µg/m³ PM2.5 (poor), about 6.0× the cleanest month (December, 7 µg/m³).

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

0204060JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateModerateGoodAug 1742 µg/m³Dec 208 µg/m³
PM2.5 (µg/m³)Level
Jan8Good
Feb9Good
Mar10Good
Apr10Good
May10Good
Jun8Good
Jul20Moderate
Aug45Poor
Sep21Moderate
Oct15Moderate
Nov9Good
Dec7Good
Location & terrain

Where is Boise?

Boise sits at 43.6°N, 116.2°W, 2,700 ft above sea level, in United States. The nearest listed city is Meridian, 9.3 mi away.

Topography around Boise

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

Within 2 miles, the terrain around Boise has only modest variations in elevation — a maximum elevation change of 535 ft around an average of 2,756 ft above sea level; within 10 miles, very significant variations in elevation — a maximum elevation change of 4,003 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 7,516 ft.

The land around Boise is covered by trees (42%) and artificial surfaces (39%) within 2 miles, grassland (55%) and trees (21%) within 10 miles, and grassland (61%) and trees (20%) within 50 miles.

2 miles
535 ft
10 miles
4,003 ft
50 miles
7,516 ft
treesshrubsgrasslandcroplandartificial surfacesbare terrainwater
December weather nearby: Meridian 9.3 mi · Eagle 9.3 mi · Kuna 14 mi · Nampa 19 mi · Caldwell 24 mi · Twin Falls 114 mi · Pendleton 191 mi · Elko 193 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 Boise (43.6135°, -116.2035°, elevation 2,700 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).