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Great Falls, Montana climate

Cfb Oceanic / temperate

Great Falls has a seasonal cool-temperate climate (Oceanic / temperate, Köppen Cfb). The hottest month is July with an average daily high near 86°F, while the coldest is January averaging around 18°F at night. Precipitation totals about 15 inches a year and is strongly seasonal — June alone averages 2.7 inches while December barely receives 0.56 inches.

☀️ Summers

Warm

Highs near 86°F in July.

About 23 days a year above 90 °F

❄️ Winters

Very cold

Lows near 18°F in January.

About 133 freezing nights a year

🌧️ Rain

Fairly dry

About 15 in of rain a year.

Wettest in June

⛅ Sky & trend

Often cloudy

Cloudy skies much of the year.

Temperature & precipitation

Daily high–low temperature range with the monthly average, plus monthly precipitation · 1991–2020 normals · hover a month for the exact figures

Clear vs cloudy days

Share of days each month that are clear, partly cloudy or cloudy · 1991–2020 · hover a month for the day counts

Great Falls climate normals (1991–2020)

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Avg high (°F)	37	39	48	58	67	75	86	84	73	59	45	37
Avg temp (°F)	27	29	37	46	54	63	70	69	59	48	36	28
Avg low (°F)	18	19	25	33	42	50	55	53	45	36	26	20
Precipitation (in)	0.6	0.6	0.6	1.8	2.7	2.7	1.3	1.3	1.4	1.1	0.7	0.6

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Avg high (°F)	37	39	48	58	67	75
Avg temp (°F)	27	29	37	46	54	63
Avg low (°F)	18	19	25	33	42	50
Precipitation (in)	0.6	0.6	0.6	1.8	2.7	2.7

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Avg high (°F)	86	84	73	59	45	37
Avg temp (°F)	70	69	59	48	36	28
Avg low (°F)	55	53	45	36	26	20
Precipitation (in)	1.3	1.3	1.4	1.1	0.7	0.6

How often — frequency of weather events

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Days with measurable rain (days)	6	8	6	9	11	9	6	5	7	6	6	6
Days with high ≥ 90°F (days)	—	—	—	—	0.1	2	12	8	2	—	—	—
Days with low ≤ 32°F (days)	23	22	20	13	3	0.2	—	—	0.7	9	17	24
Days with snowfall ≥ 1 in (days)	3	3	2	2	0.3	0.1	—	—	0.1	0.8	2	3

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Days with measurable rain (days)	6	8	6	9	11	9
Days with high ≥ 90°F (days)	—	—	—	—	0.1	2
Days with low ≤ 32°F (days)	23	22	20	13	3	0.2
Days with snowfall ≥ 1 in (days)	3	3	2	2	0.3	0.1

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Days with measurable rain (days)	6	5	7	6	6	6
Days with high ≥ 90°F (days)	12	8	2	—	—	—
Days with low ≤ 32°F (days)	—	—	0.7	9	17	24
Days with snowfall ≥ 1 in (days)	—	—	0.1	0.8	2	3

Sky & atmosphere

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Cloud cover (%)	71	69	70	70	67	61	43	47	53	65	70	68
Clear days (≤ 30% cloud)	2	3	3	3	4	5	12	11	9	5	3	3
Partly cloudy days (30–70%)	11	9	10	10	11	12	12	13	9	10	10	11
Cloudy days (≥ 70%)	18	16	18	18	17	13	7	8	12	16	17	17
Relative humidity (%)	80	75	68	62	59	58	50	49	55	63	72	77
Wind speed (mph)	7.8	7.2	6.9	6.3	5.6	5.3	4.7	4.5	5.3	6.4	7.3	7.6

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Cloud cover (%)	71	69	70	70	67	61
Clear days (≤ 30% cloud)	2	3	3	3	4	5
Partly cloudy days (30–70%)	11	9	10	10	11	12
Cloudy days (≥ 70%)	18	16	18	18	17	13
Relative humidity (%)	80	75	68	62	59	58
Wind speed (mph)	7.8	7.2	6.9	6.3	5.6	5.3

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Cloud cover (%)	43	47	53	65	70	68
Clear days (≤ 30% cloud)	12	11	9	5	3	3
Partly cloudy days (30–70%)	12	13	9	10	10	11
Cloudy days (≥ 70%)	7	8	12	16	17	17
Relative humidity (%)	50	49	55	63	72	77
Wind speed (mph)	4.7	4.5	5.3	6.4	7.3	7.6

Methodology & sources

Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Great Falls 16st (NOAA GHCN station USC00243749), about 2 km from the city centre.

Cloud, humidity, wind & sunshine — modelled estimates from NASA POWER, NASA's satellite-and-reanalysis climatology. This is the standard global source for atmospheric variables, which are not measured at most weather stations.

How we build these numbers →