Ismay, MT climate
Ismay has cold, snowy winters and warm summers, with very little rain. A typical July afternoon reaches 88°, a January night drops to 7°, and about 34 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Ismay feels like
Winter
Spring
Summer
Fall
Ismay 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 | 30° | 7° | 0.4" | 5.9" | 7 | 25 | 8° – 32° |
| February | 34° | 11° | 0.4" | 5.6" | 7 | 18 | 2° – 35° |
| March | 46° | 21° | 0.6" | 5.4" | 7 | 11 | 19° – 46° |
| April | 57° | 30° | 1.6" | 4.8" | 8 | 2 | 38° – 49° |
| May | 68° | 41° | 2.8" | 1.3" | 12 | 0 | 49° – 61° |
| June | 78° | 51° | 2.5" | 0 | 12 | 0 | 59° – 69° |
| July | 88° | 57° | 2.0" | 0 | 9 | 0 | 63° – 78° |
| August | 87° | 54° | 1.2" | 0 | 7 | 0 | 65° – 76° |
| September | 76° | 44° | 1.4" | 0.1" | 7 | 0 | 54° – 67° |
| October | 59° | 32° | 1.1" | 2.0" | 8 | 2 | 37° – 50° |
| November | 44° | 19° | 0.5" | 4.1" | 6 | 8 | 19° – 40° |
| December | 32° | 10° | 0.4" | 5.0" | 6 | 17 | 9° – 30° |
| Year | 58° | 31° | 14.7" | 34.2" | 96 | 82 |
“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 Ismay
Ismay gets 15 inches of rain and melted snow a year. May is the wettest month and January the driest. Rain or snow falls on about 96 days a year. Snow covers the ground about 82 days of the year.
About 121 frost-free days a year
In half of years the last 32° night comes by May 21 and the first one by September 20. That leaves about 121 frost-free days for gardens, shorter than 97% of U.S. towns.
Heating and cooling a home in Ismay
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Ismay, 94% of that work is heating and 6% 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 Ismay 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 Ismay averaged 1.0° warmer than the 1900s. The biggest change is in January (+3.8°). The shift is smaller than in 70% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Ismay’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 2° to 35°. June is the most reliable, staying within 10°.
Common questions about Ismay’s climate
What is the coldest month in Ismay?
January, with a typical high of 30° and a low of 7°.
What is the hottest month in Ismay?
July, with a typical high of 88° and a low of 57°. About 30 days a year reach 90°.
How much snow does Ismay get?
About 34 inches in a normal winter, most of it in January.
When is the first frost in Ismay?
In half of years the first 32° night comes by September 20, and the last spring frost by May 21.
What is the rainiest month in Ismay?
May, with 2.8 inches of rain and melted snow. The year totals 15 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Ismay itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Plevna, MT (14 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.