Will Pipes Freeze in Union County, SD? 87 nights a Year
Freeze nights in Union County
In a normal year Union County, SD gets 87 nights at or below 20°F, the point where bare pipes in a garage, attic or outside wall start to freeze. That is more than 86% of US counties.
Risk level: Severe. The risk season runs October to April, worst in January.
It depends where the pipe is
| Pipe | Freezes near | Nights a year |
|---|---|---|
| Outdoor spigot, open crawlspace | 32°F | 161 nights |
| Bare pipe in garage, attic or outside wall | 20°F | 87 nights |
| Insulated pipe in unheated space | 10°F | 47 nights |
| Inside the heated house | 0°F | 22 nights |
Foam-sleeving a bare pipe in unheated space takes it from 87 nights of risk to 47 nights. A 12 ft heat-tape kit runs $17 to $37; an average burst-pipe repair is about $500.
Month by month
Nights at or below 20°F in a normal year.
First 32°F night is usually around 10/04, last around 05/01. For 20°F: 11/03 to 04/04.
How cold Union County nights get
Average winter (Dec-Feb) low: 11°F; the coldest month, January, averages 8°F overnight. 9 months normally bring at least one night below 32°F (Jan, Feb, Mar, Apr, May, Sep, Oct, Nov, Dec). Nights below 10°F, cold enough to freeze insulated pipe in an unheated space, come in January, February, March, November, December: 47 nights a year, and 22 nights below zero.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 8°F | 12°F | 24°F | 35°F | 47°F | 58°F | 62°F | 60°F | 50°F | 37°F | 24°F | 13°F |
Union County next to its neighbours
Lincoln County, SD, 50 km north, gets 89 nights below 20°F to Union County's 87 nights. Clay County, SD, 28 km west, gets 86 nights.
| County | Distance | Below 32°F | Below 20°F | Jan low |
|---|---|---|---|---|
| Union County, SD | - | 161 nights | 87 nights | 8°F |
| Clay County, SD | 28 km west | 159 nights | 86 nights | 9°F |
| Plymouth County, IA | 37 km east | 161 nights | 88 nights | 8°F |
| Dixon County, NE | 42 km southwest | 162 nights | 87 nights | 10°F |
| Sioux County, IA | 48 km northeast | 155 nights | 83 nights | 9°F |
| Dakota County, NE | 49 km south | 157 nights | 82 nights | 10°F |
| Lincoln County, SD | 50 km north | 160 nights | 89 nights | 6°F |
Union County within SD
Union County ranks 52 of 66 SD counties for nights below 20°F. The most is Codington County, SD at 113 nights, with a 6°F average winter low. The fewest is Tripp County, SD: 75 nights, winter lows near 15°F. At 1,301 ft, Union County sits 484 ft below the state's median county elevation of 1,785 ft.
What to do here
- Treat it as a building fix, not a night-of routine: insulate, heat tape, seal crawlspace vents.
- An automatic leak shutoff pays for itself if one burst is avoided.
- Know where the main shutoff is before the first hard freeze.
The dates to be done by: when freeze season starts and ends.
Where this comes from
NOAA 1991-2020 climate normals, blended from 3 nearby stations and adjusted for elevation; closest is Hawarden, IA, 23 km away (fair match). A normal year, not tonight's forecast: check the forecast low for the night itself. Why elevation is part of the blend: how county numbers are made.