Great Falls weather in December

In December, Great Falls sees average daytime highs of 34°F and overnight lows near 20°F, with 0.8 in of precipitation across 5.7 wet days and about 8.3 hours of daylight. It is the 11th-warmest and 10th-wettest month of the year here.

Highs ease over the month, from about 36°F in the first days to 31°F by the end. The sky is clear or mostly clear about 30% of the time in December, and the air most often feels dry.

Daylight stretches from about 8 h 30 min at the start of December to 8 h 18 min by month's end. Set against the rest of the year, December is Great Falls's 7th-clearest and 1st-windiest month. For the whole year in context, see Great Falls's year-round climate.

Daytime high
34°
11th warmest
Overnight low
20°
3rd coldest
Precipitation
0.8 in
5.7 wet days
Daylight
8 h 18 min
8:14 AM – 4:29 PM
Cloud cover
60%
7th clearest
Wind
10 mph
1st windiest
Solar energy
1.39 kWh/m²
Travel score
0.0
out of 10

Great Falls is city in and county seat of Cascade County, Montana, United States.

Density
985/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 36°F in the first days to 31°F by the end.

A typical December day in Great Falls reaches about 34°F in the afternoon and slips back to 20°F overnight — a 14°F spread between the day's warmth and the night's chill. On most days the high lands between 15°F and 48°F. Set against its neighbours, December runs about 9°F cooler than November and on par with January.

20°40°60°151015202531
Avg high (°F)Avg low (°F)
13723
23722
33722
43622
53622
63622
73622
83521
93521
103521
113521
123521
133521
143420
153420
163420
173420
183420
193320
203319
213319
223319
233319
243218
253218
263218
273218
283217
293117
303117
313117

How December really feels in Great Falls

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.

Great Falls weather by month

How December compares with the rest of the year at a glance. December is the 11th-warmest and 10th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan33° / 18°0.85.75.78.70.0
Feb36° / 19°0.75.85.99.90.0
Mar45° / 26°1.075.311.61.2
Apr55° / 34°2.09.44.213.33.5
May65° / 43°2.410.81.114.95.7
Jun73° / 50°2.910.50.115.76.6
Jul84° / 56°0.95.1015.46.5
Aug83° / 55°1.14.8014.17.0
Sep71° / 47°1.46.30.212.47.3
Oct57° / 37°1.372.510.64.3
Nov43° / 27°0.95.84.79.10.7
Dec34° / 20°0.85.75.68.30.0

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 30% of the time in December.

Beyond those clear spells, partly cloudy skies cover about 17% of December, with mostly cloudy or overcast conditions the remaining 54%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14852
24951
34951
44852
54951
64951
74852
84852
94852
104852
114852
124753
134753
144852
154753
164753
174654
184654
194555
204654
214555
224654
234555
244555
254456
264357
274357
284357
294357
304258
314258

Chance of precipitation in December

Any precipitationSnow

Great Falls gets around 0.8 in of rain and snow over 5.7 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 18% and peaks near 22% on the wettest days, and about 6 days bring snow.

0%10%20%30%151015202531
Rain chance (%)Snow chance (%)
11818
21817
31717
41717
51717
61616
71616
81616
91516
101515
111516
121516
131516
141616
151617
161717
171718
181818
191819
201919
211919
222020
232020
242120
252121
262121
272221
282221
292221
302221
312221

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 10 mph in December, the windiest month of the year.

Across December, daily wind ranges from about 10 mph on the calmest days to 11 mph at its breeziest. It stays fairly steady from day to day.

051015151015202531
Wind speed (mph)Feels
110light breeze
210light breeze
310light breeze
410light breeze
510light breeze
610light breeze
710light breeze
811light breeze
911light breeze
1011light breeze
1111light breeze
1211light breeze
1311light breeze
1411light breeze
1511light breeze
1610light breeze
1710light breeze
1810light breeze
1910light breeze
2010light breeze
2110light breeze
2210light breeze
2310light breeze
2410light breeze
2510light breeze
2610light breeze
2710light breeze
2810light breeze
2910light breeze
3010light breeze
3110light breeze

Sunrise & sunset in December

DaylightNight

Daylight runs from about 8 h 30 min at the start of December to 8 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 7:59 AM to 8:20 AM, and sunset from 4:31 PM to 4:37 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
18.57:594:31
28.58:004:30
38.58:014:30
48.58:034:30
58.48:044:29
68.48:054:29
78.48:064:29
88.48:074:29
98.38:084:29
108.38:094:29
118.38:104:29
128.38:104:29
138.38:114:29
148.38:124:29
158.38:134:29
168.38:144:29
178.38:144:29
188.28:154:30
198.28:164:30
208.28:164:30
218.28:174:31
228.28:174:31
238.28:184:32
248.28:184:32
258.28:184:33
268.28:194:33
278.38:194:34
288.38:194:35
298.38:194:35
308.38:204:36
318.38:204:37

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 1.39 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 1.39 kWh/m² to a high of 7.32 kWh/m² in July across the year — December's 1.39 kWh/m² sits near the bottom.

00.511.522.5151015202531
Solar energy (kWh/m²)Level
11.5Dim
21.5Dim
31.5Dim
41.5Dim
51.4Dim
61.4Dim
71.4Dim
81.4Dim
91.4Dim
101.4Dim
111.4Dim
121.4Dim
131.4Dim
141.4Dim
151.4Dim
161.4Dim
171.4Dim
181.4Dim
191.4Dim
201.4Dim
211.4Dim
221.4Dim
231.4Dim
241.4Dim
251.4Dim
261.4Dim
271.4Dim
281.4Dim
291.4Dim
301.4Dim
311.4Dim
Planning a trip in December

Is December a good time to visit Great Falls?

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
8th-best month of the year

December is a weaker month for outdoor sightseeing in Great Falls.

What to pack for Great Falls in December

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

In December, Great Falls sees daytime highs around 34°F and nights near 20°F. Pack a warm layer and a heavy coat. About 6 days see rain.

a warm layera heavy coat

UV index in Great Falls 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 Great Falls peaks around July 14 at about 8 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 17 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 14UV 8Dec 17UV 1
UV index (midday)Level
Jan1Low
Feb2Low
Mar3Moderate
Apr4Moderate
May7High
Jun7Very high
Jul8Very high
Aug6High
Sep5Moderate
Oct4Moderate
Nov1Low
Dec1Low

Air quality in Great Falls 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 Great Falls is worst in August — around 23 µg/m³ PM2.5 (moderate), about 3.8× the cleanest month (December, 6 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodModerateGoodAug 1323 µg/m³Dec 106 µg/m³
PM2.5 (µg/m³)Level
Jan9Good
Feb6Good
Mar11Good
Apr13Moderate
May12Good
Jun9Good
Jul20Moderate
Aug23Moderate
Sep16Moderate
Oct8Good
Nov6Good
Dec6Good
Location & terrain

Where is Great Falls?

Great Falls sits at 47.5°N, 111.3°W, 3,330 ft above sea level, in United States. The nearest listed city is Helena, 71 mi away.

Topography around Great Falls

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

Within 2 miles, the terrain around Great Falls has only modest variations in elevation — a maximum elevation change of 217 ft around an average of 3,366 ft above sea level; within 10 miles, significant variations in elevation — a maximum elevation change of 1,270 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 6,588 ft.

The land around Great Falls is covered by artificial surfaces (52%) and grassland (22%) within 2 miles, grassland (51%) and cropland (38%) within 10 miles, and grassland (55%) and cropland (31%) within 50 miles.

2 miles
217 ft
10 miles
1,270 ft
50 miles
6,588 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
December weather nearby: Helena 71 mi · Butte 119 mi · Bozeman 126 mi · Missoula 134 mi · Kalispell 148 mi · Whitefish 154 mi · Lethbridge 167 mi · Medicine Hat 178 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 Great Falls (47.5002°, -111.3008°, elevation 3,330 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).