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Monthly climate in Great Falls, Montana, United States

Last updated: May 6, 2024

Under the Köppen–Geiger climate classification Great Falls features a cold semi-arid climate (BSk).Temperatures typically range between -7 °C (20 °F) and 23 °C (73 °F) through the year, but rarely can drop to -39 °C (-37 °F) or can rise to as high as 39 °C (103 °F).The average annual precipitation amounts to about 446 mm (17.6 inches) and receives 88 rainy days on the 1 mm (0.04 inches) threshold annually.Great Falls enjoys an average of 3082 hours of sunshine throughout the year, and daylight varies from 8 hours 29 minutes to 15 hours 53 minutes per day.

Monthly average temperatures in Great Falls, Montana, United States §

The warmest months in Great Falls are June, July and August, with daily mean temperatures ranging from 18 to 23 °C (64 - 73 °F) throughout the day. The coldest temperatures usually occur in January, February and December, when daily mean temperatures range from -7 to -2 °C (20 - 29 °F) throughout the day. On average each year, Great Falls experiences 70 days above 25 °C (77.0 °F) and 128 days below 0 °C (32.0 °F).

Monthly average temperatures with daily means, minimums and maximums for period, average high and low temperatures in Great Falls, Montana, United States.Generated using Copernicus Climate Change Service information.Data for period from January 2017 to June 2022.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Maximum 11°C
(52°F)		 17°C
(63°F)		 22°C
(72°F)		 29°C
(85°F)		 31°C
(88°F)		 39°C
(103°F)		 37°C
(100°F)		 39°C
(103°F)		 35°C
(96°F)		 30°C
(86°F)		 22°C
(72°F)		 18°C
(65°F)
Mean maximum 10°C
(50°F)		 12°C
(54°F)		 18°C
(64°F)		 25°C
(77°F)		 29°C
(84°F)		 31°C
(88°F)		 37°C
(98°F)		 37°C
(98°F)		 33°C
(92°F)		 26°C
(79°F)		 18°C
(64°F)		 14°C
(57°F)
Average high 1°C
(34°F)		 -2°C
(28°F)		 7°C
(44°F)		 12°C
(53°F)		 18°C
(65°F)		 24°C
(76°F)		 30°C
(87°F)		 29°C
(84°F)		 22°C
(72°F)		 13°C
(55°F)		 7°C
(45°F)		 2°C
(36°F)
Daily mean -3°C
(27°F)		 -7°C
(20°F)		 1°C
(34°F)		 6°C
(43°F)		 12°C
(55°F)		 18°C
(64°F)		 23°C
(73°F)		 21°C
(70°F)		 15°C
(60°F)		 7°C
(45°F)		 3°C
(37°F)		 -2°C
(29°F)
Average low -7°C
(20°F)		 -12°C
(11°F)		 -4°C
(26°F)		 0°C
(33°F)		 6°C
(44°F)		 11°C
(52°F)		 14°C
(58°F)		 13°C
(56°F)		 9°C
(49°F)		 2°C
(36°F)		 -1°C
(30°F)		 -5°C
(23°F)
Mean minimum -25°C
(-13°F)		 -26°C
(-15°F)		 -17°C
(1°F)		 -11°C
(12°F)		 -0°C
(32°F)		 6°C
(42°F)		 9°C
(48°F)		 7°C
(45°F)		 1°C
(34°F)		 -9°C
(16°F)		 -13°C
(9°F)		 -18°C
(-0°F)
Minimum -31°C
(-23°F)		 -39°C
(-37°F)		 -35°C
(-30°F)		 -16°C
(3°F)		 -6°C
(22°F)		 4°C
(40°F)		 6°C
(44°F)		 4°C
(40°F)		 -2°C
(29°F)		 -15°C
(4°F)		 -17°C
(1°F)		 -28°C
(-18°F)

Compare climate in Great Falls with other places

Compare temperature, precipitation, sunshine, UV index in Great Falls, Montana, United States with other places around the world.

Monthly average precipitation in Great Falls, Montana, United States §

Great Falls usually has the most precipitation in April, May and June, with an average of 10 rainy days and 65 mm (2.6 inches) of precipitation per month.The driest months in Great Falls are January, July and August. On average, 17 mm (0.7 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in Great Falls, Montana, United States.Generated using Copernicus Climate Change Service information.Data for period from January 2017 to January 2022.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Average precipitation mm (inches) 16 (0.6) 41 (1.6) 25 (1.0) 60 (2.4) 65 (2.5) 71 (2.8) 12 (0.5) 23 (0.9) 36 (1.4) 38 (1.5) 32 (1.3) 27 (1.1)
Average precipitation days (≥ 1 mm) 4 12 7 11 10 9 4 4 5 7 8 7

Monthly sunshine hours in Great Falls, Montana, United States §

The sunniest months in Great Falls are June, July and August, when the sun shines an average of 11 hours 57 minutes a day.Least sunny months in Great Falls: January, November and December receive an average of 5 hours 13 minutes of sunshine daily.

Mean monthly sunshine duration, average sunshine hours per day and mean daily daylight hours in Great Falls, Montana, United States.Generated using Copernicus Atmosphere Monitoring Service information.Data for period from January 2017 to January 2022.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Mean monthly sunshine hours 147 172 257 264 309 355 397 346 268 229 169 163
Mean daily daylight hours 8h 55m 10h 16m 11h 57m 13h 40m 15h 8m 15h 53m 15h 28m 14h 9m 12h 29m 10h 47m 9h 16m 8h 29m

Solar UV radiation in Great Falls, Montana, United States §

Great Falls experiences the highest level of ultraviolet (UV) radiation in May, June and August, when the maximum UV index can reach values of 9 - 10, which corresponds to the Very High category of sun exposure.January, November and December are in the Low / Moderate exposure category. In these months, the maximum values of the UV index do not exceed 3. For more detailed information, check out our hourly Great Falls UV Index data.

Average daily maximum UV levels by month for Great Falls, Montana, United States.Generated using Copernicus Atmosphere Monitoring Service information.Data for period from January 2022 to January 2023.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
UV Index (month maximum) 2 4 5 7 9 10 9 9 7 5 3 2