Mountain Plains, SD climate
Mountain Plains has cold, snowy winters and warm summers. A typical July afternoon reaches 86°, a January night drops to 15°, and about 71 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Mountain Plains feels like
Winter
Spring
Summer
Fall
Mountain Plains 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° | 0.8" | 8.2" | 7 | 17 | 16° – 36° |
| February | 38° | 16° | 1.1" | 12.7" | 7 | 13 | 8° – 36° |
| March | 48° | 24° | 1.4" | 12.0" | 6 | 10 | 24° – 46° |
| April | 57° | 31° | 2.6" | 8.5" | 9 | 4 | 38° – 50° |
| May | 66° | 41° | 4.2" | 2.3" | 12 | 1 | 46° – 59° |
| June | 77° | 51° | 3.7" | 0 | 12 | 0 | 58° – 70° |
| July | 86° | 57° | 2.4" | 0 | 9 | 0 | 63° – 77° |
| August | 84° | 55° | 1.9" | 0 | 7 | 0 | 64° – 75° |
| September | 75° | 46° | 1.7" | 0.1" | 6 | 0 | 54° – 66° |
| October | 59° | 34° | 2.3" | 5.5" | 7 | 2 | 37° – 52° |
| November | 47° | 24° | 1.1" | 6.3" | 5 | 6 | 25° – 45° |
| December | 38° | 16° | 0.9" | 14.9" | 5 | 16 | 18° – 34° |
| Year | 59° | 34° | 24.2" | 70.5" | 93 | 69 |
“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 Mountain Plains
Mountain Plains gets 24 inches of rain and melted snow a year. May is the wettest month and January the driest. Rain or snow falls on about 93 days a year. Snow covers the ground about 69 days of the year.
About 143 frost-free days a year
In half of years the last 32° night comes by May 12 and the first one by October 2. That leaves about 143 frost-free days for gardens, shorter than 87% of U.S. towns.
Heating and cooling a home in Mountain Plains
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Mountain Plains, 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.
How Mountain Plains 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 Mountain Plains averaged 1.0° warmer than the 1900s. The biggest change is in March (+3.1°). The shift is smaller than in 71% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Mountain Plains’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 8° to 36°. August is the most reliable, staying within 11°.
Common questions about Mountain Plains’s climate
What is the coldest month in Mountain Plains?
January, with a typical high of 37° and a low of 15°.
What is the hottest month in Mountain Plains?
July, with a typical high of 86° and a low of 57°. About 26 days a year reach 90°.
How much snow does Mountain Plains get?
About 71 inches in a normal winter, most of it in December.
When is the first frost in Mountain Plains?
In half of years the first 32° night comes by October 2, and the last spring frost by May 12.
What is the rainiest month in Mountain Plains?
May, with 4.2 inches of rain and melted snow. The year totals 24 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Mountain Plains itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Spearfish, SD (2 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.