Rocky Boy West, MT climate
Rocky Boy West has cold, snowy winters and warm summers, with very little rain. A typical July afternoon reaches 85°, a January night drops to 7°, and about 35 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Rocky Boy West feels like
Winter
Spring
Summer
Fall
Rocky Boy West 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 | 30-yr range |
|---|---|---|---|---|---|---|
| January | 29° | 7° | 0.4" | 6.4" | 7 | 5° – 33° |
| February | 34° | 10° | 0.4" | 7.3" | 5 | -4° – 36° |
| March | 45° | 20° | 0.5" | 4.0" | 5 | 14° – 40° |
| April | 57° | 30° | 1.1" | 2.7" | 8 | 38° – 47° |
| May | 67° | 39° | 2.2" | 0.7" | 11 | 49° – 59° |
| June | 75° | 48° | 3.0" | 0 | 13 | 58° – 66° |
| July | 85° | 53° | 1.7" | 0 | 8 | 59° – 76° |
| August | 84° | 51° | 1.1" | 0 | 7 | 62° – 73° |
| September | 72° | 41° | 1.2" | 0 | 7 | 52° – 63° |
| October | 57° | 30° | 1.0" | 1.9" | 7 | 36° – 50° |
| November | 42° | 19° | 0.6" | 5.2" | 6 | 18° – 40° |
| December | 32° | 10° | 0.4" | 6.4" | 5 | 7° – 31° |
| Year | 56° | 30° | 13.6" | 34.6" | 88 |
“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 Rocky Boy West
Rocky Boy West gets 14 inches of rain and melted snow a year. June is the wettest month and February the driest. Rain or snow falls on about 88 days a year.
About 130 frost-free days a year
In half of years the last 32° night comes by May 15 and the first one by September 24. That leaves about 130 frost-free days for gardens, shorter than 95% of U.S. towns.
Heating and cooling a home in Rocky Boy West
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Rocky Boy West, 95% of that work is heating and 5% 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.
How Rocky Boy West 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 Rocky Boy West averaged 1.7° warmer than the 1900s. The biggest change is in January (+4.9°). The shift is larger than in 81% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Rocky Boy West’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 -4° to 36°. June is the most reliable, staying within 8°.
Common questions about Rocky Boy West’s climate
What is the coldest month in Rocky Boy West?
January, with a typical high of 29° and a low of 7°.
What is the hottest month in Rocky Boy West?
July, with a typical high of 85° and a low of 53°. About 27 days a year reach 90°.
How much snow does Rocky Boy West get?
About 35 inches in a normal winter, most of it in February.
When is the first frost in Rocky Boy West?
In half of years the first 32° night comes by September 24, and the last spring frost by May 15.
What is the rainiest month in Rocky Boy West?
June, with 3.0 inches of rain and melted snow. The year totals 14 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Rocky Boy West itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Ft Assiniboine, MT (16 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.