Union, SD climate
Union has cold, snowy winters and pleasant summers. A typical July afternoon reaches 81°, a January night drops to 3°, and about 43 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decade13° warmer than normal today. The forecast high is 76°, and a typical Sep 30 in Union peaks around 63°.Live forecast: National Weather Service · Normal: NOAA 1991–2020
What a year in Union feels like
Winter
Spring
Summer
Fall
Union 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 | 30-yr range |
|---|---|---|---|---|---|---|
| January | 20° | 3° | 0.6" | 9.6" | 5 | -2° – 25° |
| February | 25° | 7° | 0.6" | 7.9" | 4 | 0° – 28° |
| March | 38° | 19° | 1.0" | 5.1" | 4 | 19° – 43° |
| April | 53° | 32° | 2.0" | 5.0" | 6 | 32° – 51° |
| May | 66° | 44° | 3.1" | 0 | 10 | 50° – 62° |
| June | 76° | 55° | 4.0" | 0 | 10 | 60° – 69° |
| July | 81° | 60° | 3.8" | 0 | 9 | 62° – 77° |
| August | 80° | 58° | 2.6" | 0 | 7 | 63° – 73° |
| September | 71° | 48° | 2.4" | 0 | 7 | 53° – 65° |
| October | 56° | 35° | 2.2" | 1.4" | 6 | 38° – 51° |
| November | 39° | 21° | 0.7" | 6.0" | 4 | 18° – 41° |
| December | 25° | 9° | 0.7" | 7.8" | 5 | 3° – 25° |
| Year | 53° | 33° | 23.6" | 42.8" | 77 |
“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 Union
Union gets 24 inches of rain and melted snow a year. June is the wettest month and January the driest. Rain or snow falls on about 77 days a year.
About 150 frost-free days a year
In half of years the last 32° night comes by May 6 and the first one by October 4. That leaves about 150 frost-free days for gardens, shorter than 81% of U.S. towns.
Heating and cooling a home in Union
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Union, 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.
Union and its neighbors
Union borders 4 towns with climate data. January nights across them vary by 0.7°. Homer has the coldest January nights (2°) and Andover the hottest July afternoons (83°). Union’s January low is 3° and its July high 81°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Union 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 Union averaged 1.1° warmer than the 1900s. The biggest change is in January (+3.1°). The shift is smaller than in 58% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Union’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 0° to 28°. August is the most reliable, staying within 9°.
Common questions about Union’s climate
What is the coldest month in Union?
January, with a typical high of 20° and a low of 3°.
What is the hottest month in Union?
July, with a typical high of 81° and a low of 60°. About 11 days a year reach 90°.
How much snow does Union get?
About 43 inches in a normal winter, most of it in January.
When is the first frost in Union?
In half of years the first 32° night comes by October 4, and the last spring frost by May 6.
What is the rainiest month in Union?
June, with 4.0 inches of rain and melted snow. The year totals 24 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Union itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Webster, SD (15 mi, snow) and Andover #2, SD (7 mi, frost, heat and degree days). Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.