Joliet, MT climate
Joliet has cold, snowy winters and warm summers, with very little rain. A typical July afternoon reaches 86°, a January night drops to 15°, and about 51 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Joliet feels like
Winter
Spring
Summer
Fall
Joliet 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 | 37° | 15° | 0.5" | 7.7" | 5 | 19 | 17° – 36° |
| February | 39° | 17° | 0.5" | 9.5" | 5 | 12 | 10° – 39° |
| March | 50° | 24° | 0.8" | 8.0" | 6 | 6 | 26° – 45° |
| April | 57° | 32° | 1.7" | 4.1" | 9 | 3 | 38° – 49° |
| May | 66° | 40° | 2.4" | 0.8" | 11 | 0 | 49° – 58° |
| June | 76° | 48° | 2.1" | 0 | 10 | 0 | 56° – 67° |
| July | 86° | 54° | 1.1" | 0 | 7 | 0 | 61° – 76° |
| August | 85° | 52° | 0.8" | 0 | 6 | 0 | 63° – 73° |
| September | 74° | 44° | 1.3" | 0.4" | 6 | 0 | 55° – 66° |
| October | 59° | 34° | 1.4" | 4.8" | 7 | 3 | 38° – 52° |
| November | 46° | 24° | 0.6" | 6.5" | 5 | 6 | 25° – 44° |
| December | 36° | 16° | 0.5" | 9.1" | 5 | 17 | 16° – 33° |
| Year | 59° | 33° | 13.6" | 50.9" | 81 | 66 |
“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 Joliet
Joliet gets 14 inches of rain and melted snow a year. May is the wettest month and February the driest. Rain or snow falls on about 81 days a year. Snow covers the ground about 66 days of the year.
About 107 frost-free days a year
In half of years the last 32° night comes by May 29 and the first one by September 15. That leaves about 107 frost-free days for gardens, shorter than 99% of U.S. towns.
Heating and cooling a home in Joliet
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Joliet, 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 Joliet 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 Joliet 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 Joliet’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 10° to 39°. May is the most reliable, staying within 9°.
Common questions about Joliet’s climate
What is the coldest month in Joliet?
January, with a typical high of 37° and a low of 15°.
What is the hottest month in Joliet?
July, with a typical high of 86° and a low of 54°. About 29 days a year reach 90°.
How much snow does Joliet get?
About 51 inches in a normal winter, most of it in February.
When is the first frost in Joliet?
In half of years the first 32° night comes by September 15, and the last spring frost by May 29.
What is the rainiest month in Joliet?
May, with 2.4 inches of rain and melted snow. The year totals 14 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Joliet itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Joliet, MT (2 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.