Hamilton, MT climate
Hamilton has chilly winters and warm summers, with very little rain. A typical July afternoon reaches 86°, a January night drops to 20°, and about 17 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Hamilton feels like
Winter
Spring
Summer
Fall
Hamilton 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 | 36° | 20° | 1.0" | 4.0" | 9 | 8 | 16° – 34° |
| February | 40° | 21° | 1.0" | 3.0" | 8 | 7 | 22° – 37° |
| March | 50° | 27° | 0.9" | 1.5" | 10 | 2 | 30° – 44° |
| April | 58° | 32° | 1.0" | 0.1" | 9 | 0 | 41° – 51° |
| May | 68° | 39° | 1.5" | 0 | 10 | 0 | 48° – 58° |
| June | 75° | 45° | 1.7" | 0 | 10 | 0 | 56° – 67° |
| July | 86° | 50° | 0.8" | 0 | 6 | 0 | 58° – 74° |
| August | 84° | 48° | 0.8" | 0 | 6 | 0 | 61° – 69° |
| September | 74° | 41° | 0.9" | 0 | 7 | 0 | 54° – 62° |
| October | 58° | 32° | 1.0" | 0.1" | 9 | 0 | 39° – 51° |
| November | 43° | 25° | 1.3" | 1.6" | 9 | 2 | 27° – 40° |
| December | 34° | 19° | 1.3" | 6.8" | 9 | 5 | 20° – 31° |
| Year | 59° | 33° | 13.2" | 17.1" | 100 | 24 |
“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 Hamilton
Hamilton gets 13 inches of rain and melted snow a year. June is the wettest month and August the driest. Rain or snow falls on about 100 days a year. Snow covers the ground about 24 days of the year.
About 122 frost-free days a year
In half of years the last 32° night comes by May 21 and the first one by September 22. That leaves about 122 frost-free days for gardens, shorter than 97% of U.S. towns.
Heating and cooling a home in Hamilton
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Hamilton, 97% of that work is heating and 3% 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 Hamilton 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 Hamilton averaged 1.0° warmer than the 1900s. The biggest change is in January (+3.6°). The shift is smaller than in 68% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Hamilton’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. January swings the most: between 1991 and 2020 its average temperature ranged from 16° to 34°. September is the most reliable, staying within 8°.
Common questions about Hamilton’s climate
What is the coldest month in Hamilton?
December, with a typical high of 34° and a low of 19°.
What is the hottest month in Hamilton?
July, with a typical high of 86° and a low of 50°. About 22 days a year reach 90°.
How much snow does Hamilton get?
About 17 inches in a normal winter, most of it in December.
When is the first frost in Hamilton?
In half of years the first 32° night comes by September 22, and the last spring frost by May 21.
What is the rainiest month in Hamilton?
June, with 1.7 inches of rain and melted snow. The year totals 13 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Hamilton itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Stevensville, MT (18 mi, snow) and Hamilton, MT (1 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.