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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 30°C, while the coldest is January averaging around −8°C at night. Precipitation totals about 392 mm a year and is strongly seasonal — June alone averages 70 mm while December barely receives 14 mm.

☀️ Summers

Warm

Highs near 30°C in July.

About 23 days a year above 32 °C

❄️ Winters

Very cold

Lows near −8°C in January.

About 133 freezing nights a year

🌧️ Rain

Fairly dry

About 392 mm 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 (°C)	3	4	9	15	19	24	30	29	23	15	7	3
Avg temp (°C)	−3	−2	3	8	12	17	21	20	15	9	2	−2
Avg low (°C)	−8	−7	−4	1	6	10	13	12	7	2	−3	−7
Precipitation (mm)	15	15	16	45	68	70	34	33	35	29	18	14

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Avg high (°C)	3	4	9	15	19	24
Avg temp (°C)	−3	−2	3	8	12	17
Avg low (°C)	−8	−7	−4	1	6	10
Precipitation (mm)	15	15	16	45	68	70

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Avg high (°C)	30	29	23	15	7	3
Avg temp (°C)	21	20	15	9	2	−2
Avg low (°C)	13	12	7	2	−3	−7
Precipitation (mm)	34	33	35	29	18	14

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 ≥ 32°C (days)	—	—	—	—	0.1	2	12	8	2	—	—	—
Days with low ≤ 0°C (days)	23	22	20	13	3	0.2	—	—	0.7	9	17	24
Days with snowfall ≥ 2.5 cm (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 ≥ 32°C (days)	—	—	—	—	0.1	2
Days with low ≤ 0°C (days)	23	22	20	13	3	0.2
Days with snowfall ≥ 2.5 cm (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 ≥ 32°C (days)	12	8	2	—	—	—
Days with low ≤ 0°C (days)	—	—	0.7	9	17	24
Days with snowfall ≥ 2.5 cm (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 (m/s)	3.5	3.2	3.1	2.8	2.5	2.4	2.1	2.0	2.4	2.9	3.3	3.4

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 (m/s)	3.5	3.2	3.1	2.8	2.5	2.4

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 (m/s)	2.1	2.0	2.4	2.9	3.3	3.4

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 →