Harrison, MT climate
Harrison has chilly winters and pleasant summers, with very little rain. A typical July afternoon reaches 84°, a January night drops to 16°.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Harrison feels like
Winter
Spring
Summer
Fall
Harrison weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
| Month | High | Low | Rain + melt | 30-yr range |
|---|---|---|---|---|
| January | 37° | 16° | 0.5" | 18° – 33° |
| February | 39° | 17° | 0.6" | 17° – 37° |
| March | 48° | 24° | 1.1" | 29° – 42° |
| April | 55° | 30° | 1.9" | 37° – 47° |
| May | 65° | 38° | 2.6" | 46° – 56° |
| June | 73° | 44° | 2.6" | 54° – 65° |
| July | 84° | 49° | 1.3" | 57° – 73° |
| August | 83° | 47° | 1.1" | 59° – 69° |
| September | 72° | 40° | 1.5" | 52° – 61° |
| October | 58° | 31° | 1.3" | 37° – 51° |
| November | 44° | 22° | 0.7" | 25° – 42° |
| December | 35° | 15° | 0.6" | 18° – 30° |
| Year | 58° | 31° | 15.6" |
“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 Harrison
Harrison gets 16 inches of rain and melted snow a year. June is the wettest month and January the driest.
About 139 frost-free days a year
In half of years the last 32° night comes by May 9 and the first one by September 27. That leaves about 139 frost-free days for gardens, shorter than 90% of U.S. towns.
Heating and cooling a home in Harrison
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Harrison, 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.
How Harrison 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 Harrison averaged 1.4° warmer than the 1900s. The biggest change is in January (+4.2°). The shift is larger than in 62% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Harrison’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 17° to 37°. September is the most reliable, staying within 8°.
Common questions about Harrison’s climate
What is the coldest month in Harrison?
December, with a typical high of 35° and a low of 15°.
What is the hottest month in Harrison?
July, with a typical high of 84° and a low of 49°. About 25 days a year reach 90°.
When is the first frost in Harrison?
In half of years the first 32° night comes by September 27, and the last spring frost by May 9.
What is the rainiest month in Harrison?
June, with 2.6 inches of rain and melted snow. The year totals 16 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Harrison itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Trident, MT (22 mi, frost, heat and degree days). Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.