Potomac, MT climate
Potomac has cold, snowy winters and pleasant summers, with very little rain. A typical July afternoon reaches 83°, a January night drops to 13°, and about 52 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Potomac feels like
Winter
Spring
Summer
Fall
Potomac 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 | 32° | 13° | 1.1" | 15.5" | 8 | 30 | 13° – 30° |
| February | 37° | 14° | 1.0" | 7.2" | 6 | 25 | 12° – 33° |
| March | 47° | 22° | 0.8" | 4.6" | 6 | 14 | 26° – 41° |
| April | 55° | 28° | 1.1" | 1.3" | 6 | 1 | 37° – 49° |
| May | 65° | 35° | 1.7" | 0.4" | 8 | 0 | 45° – 55° |
| June | 73° | 41° | 2.1" | 0 | 10 | 0 | 53° – 66° |
| July | 83° | 45° | 0.8" | 0 | 5 | 0 | 55° – 72° |
| August | 83° | 44° | 0.9" | 0 | 4 | 0 | 58° – 67° |
| September | 72° | 37° | 1.0" | 0.2" | 5 | 0 | 51° – 60° |
| October | 56° | 28° | 1.3" | 1.9" | 7 | 1 | 35° – 49° |
| November | 40° | 21° | 1.3" | 7.4" | 8 | 7 | 24° – 38° |
| December | 31° | 13° | 1.3" | 13.3" | 8 | 24 | 15° – 28° |
| Year | 56° | 28° | 14.3" | 51.8" | 81 | 102 |
“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 Potomac
Potomac gets 14 inches of rain and melted snow a year. June is the wettest month and March the driest. Rain or snow falls on about 81 days a year. Snow covers the ground about 102 days of the year.
A year-round growing season
Heating and cooling a home in Potomac
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Potomac, 99% of that work is heating and 1% 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 Potomac 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 Potomac averaged 1.4° warmer than the 1900s. The biggest change is in January (+4.1°). The shift is larger than in 63% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Potomac’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 12° to 33°. September is the most reliable, staying within 9°.
Common questions about Potomac’s climate
What is the coldest month in Potomac?
December, with a typical high of 31° and a low of 13°.
What is the hottest month in Potomac?
July, with a typical high of 83° and a low of 45°. About 16 days a year reach 90°.
How much snow does Potomac get?
About 52 inches in a normal winter, most of it in January.
When is the first frost in Potomac?
Frost is uncommon. Only 100% of years see a night at 32° or below.
What is the rainiest month in Potomac?
June, with 2.1 inches of rain and melted snow. The year totals 14 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Potomac itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Potomac, MT (1 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.