Great Falls, MT climate
Great Falls has cold, snowy winters and warm summers, with very little rain. A typical July afternoon reaches 84°, a January night drops to 13°, and about 66 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Great Falls feels like
Winter
Spring
Summer
Fall
Great Falls weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 35° | 13° | 0.5" | 9.2" | 7 | 14 | 12° – 36° |
| February | 38° | 14° | 0.5" | 10.1" | 8 | 11 | -1° – 38° |
| March | 47° | 22° | 0.6" | 10.1" | 8 | 8 | 17° – 43° |
| April | 56° | 30° | 1.5" | 9.4" | 10 | 3 | 37° – 48° |
| May | 66° | 39° | 2.3" | 1.9" | 11 | 1 | 48° – 58° |
| June | 74° | 46° | 2.7" | 0.3" | 12 | 0 | 56° – 66° |
| July | 84° | 52° | 1.1" | 0 | 7 | 0 | 58° – 77° |
| August | 84° | 50° | 1.1" | 0.3" | 7 | 0 | 61° – 71° |
| September | 73° | 43° | 1.3" | 0.8" | 7 | 0 | 53° – 64° |
| October | 58° | 32° | 0.9" | 5.2" | 7 | 3 | 36° – 52° |
| November | 44° | 23° | 0.6" | 9.2" | 7 | 8 | 21° – 43° |
| December | 36° | 16° | 0.4" | 9.6" | 7 | 11 | 14° – 35° |
| Year | 58° | 32° | 13.4" | 66.1" | 98 | 60 |
“Wet days” have at least 0.01" of rain or melted snow. “Snow on ground” counts days with 1" or more. The 30-year range is the coldest and warmest that month’s average temperature got between 1991 and 2020.
Rain and snow in Great Falls
Great Falls gets 13 inches of rain and melted snow a year. June is the wettest month and December the driest. Rain or snow falls on about 98 days a year. Snow covers the ground about 60 days of the year.
About 126 frost-free days a year
In half of years the last 32° night comes by May 19 and the first one by September 24. That leaves about 126 frost-free days for gardens, shorter than 96% of U.S. towns.
Heating and cooling a home in Great Falls
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Great Falls, 96% of that work is heating and 4% is cooling, so the furnace matters far more than the air conditioner.
Degree days measure how far each day’s average temperature falls below or rises above 65°, added up over a year. Source: NOAA station normals.
Great Falls and its neighbors
Great Falls borders 3 towns with climate data. January nights across them vary by 0.2°. Malmstrom AFB has the coldest January nights (13°) and Black Eagle the hottest July afternoons (84°). Great Falls’s January low is 13° and its July high 84°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Great Falls compares
Compared with every U.S. town and city on TownTapestry, each counted once.
Warmer than it used to be
The last 30 years in Great Falls averaged 1.4° warmer than the 1900s. The biggest change is in January (+5.0°). The shift is larger than in 63% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Great Falls’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. February swings the most: between 1991 and 2020 its average temperature ranged from -1° to 38°. June is the most reliable, staying within 10°.
Common questions about Great Falls’s climate
What is the coldest month in Great Falls?
January, with a typical high of 35° and a low of 13°.
What is the hottest month in Great Falls?
July, with a typical high of 84° and a low of 52°. About 22 days a year reach 90°.
How much snow does Great Falls get?
About 66 inches in a normal winter, most of it in February.
When is the first frost in Great Falls?
In half of years the first 32° night comes by September 24, and the last spring frost by May 19.
What is the rainiest month in Great Falls?
June, with 2.7 inches of rain and melted snow. The year totals 13 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Great Falls itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Great Falls Intl Airport, MT (4 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.