Winter nights in Union Township are colder than in 94% of U.S. towns
On a normal July day the thermometer tops out near 87°. It is a dry place: less rain and snow fall here than on 91% of U.S. towns. The latest 30-year average runs 1.0° warmer than 1901–2000’s, with January up the most. The frost-free window for a garden runs roughly May 15 to September 27.
A year in Union Township at a glance
Each month’s typical high and low, and what it brings.
What stands out about Union Township’s climate
Compared with towns across the U.S., with Union Township’s place in South Dakota beside it.
What a year in Union Township feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 134 frost-free days a year
In half of years the last 32° night comes by May 15 and the first by September 27. Frost and day counts come from NOAA’s station at Plainview 6 Ssw, SD, 9 miles from the town’s center, 100 ft lower.
The 2023 USDA map puts Union Township’s center in zone 4b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −21°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 43 inches of snow a winter
Snow, measured at Plainview 6 Ssw, SD, is heaviest from March through April, about 8 inches a month. Precipitation (rain plus melted snow) adds up to 18 inches a year; May is the wettest month and January the driest. Rain or snow falls on about 67 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Union Township
93% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through April.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Plainview 6 Ssw, SD.
Living with Union Township’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
134 frost-free days in zone 4b. The last frost comes by May 15 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Sep 27.
Months with highs of 62–84° and lows of 40° or more: May, June and September.
Parks & trails →Of the yearly building losses FEMA expects in Union Township from natural hazards, river flooding is the largest share (38%); heat waves, cold waves, winter storms and ice storms together are 16%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Union Township and its neighbors
Every town next door is within a degree of Union Township in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Union Township’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Union Township, SD | 10° | 87° | 18" | 43" |
| Alliance, NE | 13° | 88° | 17" | 45" |
| Gypsum, CO | 11° | 86° | 14" | 39" |
| Sheridan, WY | 11° | 89° | 15" | 33" |
| Lockwood, MT | 15° | 88° | 15" | 35" |
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value. Snow and frost-free days come from the nearest weather station, so neighbors often share them.
Warmer than it used to be
The last 30 years in Union Township averaged 1.0° warmer than the 1900s. The biggest change is in January (+3.5°).
A smaller shift than in 75% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How Union Township compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Union Township’s place among South Dakota’s.
Union Township weather by month
Highs, lows and precipitation from NOAA’s grid at Union Township’s center; snow, wet days and snow on the ground from Plainview 6 Ssw, SD. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | 30-yr range |
|---|---|---|---|---|---|---|
| January | 31° | 10° | 0.4" | 5.0" | 4 | 11° – 35° |
| February | 35° | 13° | 0.6" | 5.1" | 4 | 5° – 36° |
| March | 46° | 23° | 0.9" | 8.8" | 5 | 21° – 47° |
| April | 58° | 32° | 1.9" | 8.1" | 7 | 37° – 51° |
| May | 68° | 43° | 3.4" | 0.9" | 9 | 49° – 61° |
| June | 79° | 53° | 3.1" | 0.0" | 10 | 61° – 71° |
| July | 87° | 59° | 2.5" | 0.0" | 7 | 64° – 80° |
| August | 86° | 57° | 1.6" | 0.0" | 5 | 65° – 77° |
| September | 77° | 47° | 1.3" | 0.0" | 4 | 55° – 68° |
| October | 60° | 34° | 1.6" | 3.4" | 5 | 39° – 53° |
| November | 45° | 22° | 0.5" | 4.1" | 3 | 22° – 43° |
| December | 34° | 13° | 0.5" | 7.1" | 3 | 11° – 33° |
| Year | 59° | 34° | 18.1" | 42.5" | 67 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 5° to 36°. June is the most reliable, staying within 10°.
Where Union Township’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Union Township’s center.
- Snow: Plainview 6 Ssw, SD.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Plainview 6 Ssw, SD, 9 miles from the town’s center, 100 ft lower; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Union Township’s climate
What is the weather like in Union Township?
A typical July afternoon reaches 87°, a January night drops to 10°, and about 43 inches of snow falls in a normal winter. Colder January nights than 94% of U.S. towns; hotter July afternoons than 62% of U.S. towns.
How cold does it get in Union Township in winter?
January nights average 10°. About 181 nights a year reach 32° or below and 24 reach 0° or below. In the coldest January of the last 30 years the month averaged 11°.
How much snow does Union Township get?
About 43 inches in a normal winter at Plainview 6 Ssw, SD, heaviest from March through April, about 8 inches a month.
How hot does it get in Union Township?
July, with a typical high of 87° and a low of 59°. About 37 days a year reach 90° and 8 reach 100° (Plainview 6 Ssw, SD).
When is the first and last frost in Union Township?
In half of years the last spring frost (32°) comes by May 15 and the first fall frost by September 27, about 134 frost-free days, at Plainview 6 Ssw, SD.
What growing zone is Union Township in?
Zone 4b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −21°.
What is the best time of year to visit Union Township?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Union Township getting warmer?
Yes: 1991–2020 averaged 1.0° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 75% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Union Township.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.