St. Mary, MN climate
St. Mary has cold, snowy winters and pleasant summers. A typical July afternoon reaches 81°, a January night drops to 6°, and about 52 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in St. Mary feels like
Winter
Spring
Summer
Fall
St. Mary 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 | 23° | 6° | 0.9" | 10.7" | 9 | 26 | 4° – 27° |
| February | 27° | 10° | 0.9" | 10.8" | 8 | 22 | 6° – 31° |
| March | 40° | 23° | 1.8" | 9.0" | 10 | 13 | 24° – 48° |
| April | 56° | 35° | 3.3" | 3.0" | 12 | 2 | 33° – 54° |
| May | 68° | 47° | 4.4" | 0.4" | 14 | 0 | 51° – 65° |
| June | 78° | 58° | 5.3" | 0 | 13 | 0 | 64° – 73° |
| July | 81° | 61° | 4.7" | 0 | 11 | 0 | 64° – 77° |
| August | 79° | 58° | 4.6" | 0 | 11 | 0 | 64° – 73° |
| September | 72° | 50° | 3.7" | 0 | 10 | 0 | 54° – 67° |
| October | 59° | 37° | 2.6" | 0.7" | 10 | 0 | 41° – 53° |
| November | 42° | 25° | 1.6" | 5.8" | 8 | 6 | 23° – 46° |
| December | 28° | 13° | 1.2" | 11.9" | 9 | 21 | 6° – 30° |
| Year | 54° | 35° | 35.0" | 52.3" | 124 | 90 |
“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 St. Mary
St. Mary gets 35 inches of rain and melted snow a year. June is the wettest month and January the driest. Rain or snow falls on about 124 days a year. Snow covers the ground about 90 days of the year.
About 155 frost-free days a year
In half of years the last 32° night comes by May 2 and the first one by October 4. That leaves about 155 frost-free days for gardens, shorter than 76% of U.S. towns.
Heating and cooling a home in St. Mary
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In St. Mary, 93% of that work is heating and 7% 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.
St. Mary and its neighbors
St. Mary borders 5 towns with climate data. January nights across them vary by 0.1°. Alton has both the coldest January nights (6°) and the hottest July afternoons (82°). St. Mary’s January low is 6° and its July high 81°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How St. Mary 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 St. Mary averaged 1.0° warmer than the 1900s. The biggest change is in December (+3.1°). The shift is smaller than in 74% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at St. Mary’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 6° to 31°. June is the most reliable, staying within 8°.
Common questions about St. Mary’s climate
What is the coldest month in St. Mary?
January, with a typical high of 23° and a low of 6°.
What is the hottest month in St. Mary?
July, with a typical high of 81° and a low of 61°. About 10 days a year reach 90°.
How much snow does St. Mary get?
About 52 inches in a normal winter, most of it in December.
When is the first frost in St. Mary?
In half of years the first 32° night comes by October 4, and the last spring frost by May 2.
What is the rainiest month in St. Mary?
June, with 5.3 inches of rain and melted snow. The year totals 35 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for St. Mary itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Waseca S Rsch & Outreach Ctr, MN (3 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.