Helena weather in December

In December, Helena sees average daytime highs of 27°F and overnight lows near 12°F, with 1.1 in of precipitation across 7.3 wet days and about 8.4 hours of daylight. It is the 12th-warmest and 10th-wettest month of the year here.

Highs ease over the month, from about 30°F in the first days to 26°F by the end. The sky is clear or mostly clear about 20% of the time in December, and the air most often feels dry.

Daylight stretches from about 8 h 36 min at the start of December to 8 h 24 min by month's end. Set against the rest of the year, December is Helena's 8th-clearest and 2nd-windiest month. For the whole year in context, see Helena's year-round climate.

Daytime high
27°
12th warmest
Overnight low
12°
2nd coldest
Precipitation
1.1 in
7.3 wet days
Daylight
8 h 24 min
8:13 AM – 4:36 PM
Cloud cover
65%
8th clearest
Wind
6 mph
2nd windiest
Solar energy
1.55 kWh/m²
Travel score
0.0
out of 10

Helena is capital city of the U.S. state of Montana and seat of Lewis and Clark County.

Density
749/km²
people per km²
Founded
1864

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 30°F in the first days to 26°F by the end.

A typical December day in Helena reaches about 27°F in the afternoon and slips back to 12°F overnight — a 15°F spread between the day's warmth and the night's chill. On most days the high lands between 15°F and 38°F. Set against its neighbours, December runs about 10°F cooler than November and on par with January.

20°40°151015202531
Avg high (°F)Avg low (°F)
13015
23015
32915
42914
52914
62914
72813
82813
92813
102813
112813
122813
132813
142713
152712
162712
172712
182712
192712
202612
212611
222611
232611
242611
252611
262611
272611
282611
292611
302611
312611

How December really feels in Helena

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
31 feel bitter (≤ 14°F)

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

Helena weather by month

How December compares with the rest of the year at a glance. December is the 12th-warmest and 10th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan28° / 12°0.977.68.80.0
Feb31° / 13°0.977.6100.0
Mar39° / 20°1.49.77.711.60.1
Apr48° / 28°2.411.97.213.31.7
May59° / 37°3.213.82.714.84.0
Jun67° / 44°3.813.50.615.65.7
Jul78° / 50°1.78.8015.27.2
Aug78° / 49°1.57.50.1147.4
Sep67° / 42°1.66.80.912.46.7
Oct52° / 32°1.58.33.810.72.9
Nov37° / 21°1.27.76.29.20.1
Dec27° / 12°1.17.37.88.40.0

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 20% of the time in December.

Beyond those clear spells, partly cloudy skies cover about 18% of December, with mostly cloudy or overcast conditions the remaining 61%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14060
24060
34159
44159
54159
64060
74060
84060
94060
104060
114060
123961
133862
143862
153862
163862
173763
183763
193763
203763
213763
223763
233763
243763
253763
263763
273862
283862
293862
303862
313862

Chance of precipitation in December

Any precipitationSnow

Helena gets around 1.1 in of rain and snow over 7.3 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 23% and peaks near 26% on the wettest days, and about 8 days bring snow.

0%10%20%30%40%151015202531
Rain chance (%)Snow chance (%)
12424
22324
32323
42223
52223
62223
72122
82122
92122
102122
112122
122122
132122
142223
152223
162224
172324
182324
192325
202425
212426
222526
232527
242527
252627
262627
272627
282627
292627
302627
312527

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 6 mph in December.

Across December, daily wind ranges from about 6 mph on the calmest days to 6 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (mph)Feels
16calm
26calm
36calm
46calm
56calm
66calm
76calm
86calm
96calm
106calm
116calm
126calm
136calm
146calm
156calm
166calm
176calm
186calm
196calm
206calm
216calm
226calm
236calm
246calm
256calm
266calm
276calm
286calm
296calm
306calm
316calm

Sunrise & sunset in December

DaylightNight

Daylight runs from about 8 h 36 min at the start of December to 8 h 24 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 7:59 AM to 8:19 AM, and sunset from 4:37 PM to 4:44 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
18.67:594:37
28.68:004:37
38.68:014:36
48.68:024:36
58.58:034:36
68.58:044:36
78.58:054:36
88.58:064:35
98.58:074:35
108.58:084:35
118.48:094:35
128.48:104:35
138.48:104:35
148.48:114:36
158.48:124:36
168.48:134:36
178.48:134:36
188.48:144:36
198.48:154:37
208.48:154:37
218.48:164:38
228.48:164:38
238.48:174:38
248.48:174:39
258.48:174:40
268.48:184:40
278.48:184:41
288.48:184:42
298.48:194:42
308.48:194:43
318.48:194:44

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 1.55 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 1.55 kWh/m² to a high of 7.45 kWh/m² in July across the year — December's 1.55 kWh/m² sits near the bottom.

00.511.522.5151015202531
Solar energy (kWh/m²)Level
11.7Dim
21.6Dim
31.6Dim
41.6Dim
51.6Dim
61.6Dim
71.6Dim
81.6Dim
91.6Dim
101.6Dim
111.5Dim
121.5Dim
131.5Dim
141.5Dim
151.5Dim
161.5Dim
171.5Dim
181.5Dim
191.5Dim
201.5Dim
211.5Dim
221.5Dim
231.5Dim
241.5Dim
251.5Dim
261.6Dim
271.6Dim
281.6Dim
291.6Dim
301.6Dim
311.6Dim
Planning a trip in December

Hazard calendar for Helena

In seasonPeak

None of Helena's seasonal hazards are active in December. The full-year calendar below shows when the rainy season, cyclone risk and dust haze do peak.

Helena's rainy season runs April–June, 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 Helena?

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

0.0
Sightseeing
10th-best month of the year
0.0
Beach & pool
7th-best month of the year

December is a weaker month for outdoor sightseeing in Helena.

What to pack for Helena in December

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

In December, Helena sees daytime highs around 27°F and nights near 12°F. Pack a warm layer and a heavy coat. About 7 days see rain.

a warm layera heavy coat

UV index in Helena 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 Helena peaks around July 15 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 21 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 15UV 9Dec 21UV 1
UV index (midday)Level
Jan1Low
Feb2Low
Mar5Moderate
Apr5Moderate
May7High
Jun8Very high
Jul9Very high
Aug7Very high
Sep5High
Oct3Moderate
Nov2Low
Dec1Low

Air quality in Helena 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 Helena is worst in August — around 25 µg/m³ PM2.5 (moderate), about 3.1× the cleanest month (December, 8 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodAug 1225 µg/m³Dec 178 µg/m³
PM2.5 (µg/m³)Level
Jan9Good
Feb9Good
Mar11Good
Apr11Good
May11Good
Jun9Good
Jul23Moderate
Aug25Moderate
Sep17Moderate
Oct8Good
Nov9Good
Dec8Good
Location & terrain

Where is Helena?

Helena sits at 46.6°N, 112.0°W, 4,058 ft above sea level, in United States. The nearest listed city is Butte, 47 mi away.

Topography around Helena

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

Within 2 miles, the terrain around Helena has significant variations in elevation — a maximum elevation change of 1,588 ft around an average of 4,219 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 3,481 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 6,729 ft.

The land around Helena is covered by artificial surfaces (45%), trees (28%) and grassland (25%) within 2 miles, grassland (53%) and trees (31%) within 10 miles, and grassland (53%) and trees (42%) within 50 miles.

2 miles
1,588 ft
10 miles
3,481 ft
50 miles
6,729 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
December weather nearby: Butte 47 mi · Great Falls 71 mi · Bozeman 79 mi · Missoula 94 mi · Kalispell 153 mi · Whitefish 165 mi · Billings 178 mi · Rexburg 191 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 Helena (46.5927°, -112.0361°, elevation 4,058 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).