Will Pipes Freeze in Lyman County, SD? 90 nights a Year
Freeze nights in Lyman County
In a normal year Lyman County, SD gets 90 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 88% 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 | 166 nights |
| Bare pipe in garage, attic or outside wall | 20°F | 90 nights |
| Insulated pipe in unheated space | 10°F | 46 nights |
| Inside the heated house | 0°F | 20 nights |
Foam-sleeving a bare pipe in unheated space takes it from 90 nights of risk to 46 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 09/28, last around 05/12. For 20°F: 10/25 to 04/13.
How cold Lyman County nights get
Average winter (Dec-Feb) low: 12°F; the coldest month, January, averages 9°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, April, November, December: 46 nights a year, and 20 nights below zero.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 9°F | 13°F | 23°F | 33°F | 45°F | 56°F | 61°F | 59°F | 50°F | 36°F | 22°F | 13°F |
Lyman County next to its neighbours
Buffalo County, SD, 54 km east, gets 108 nights below 20°F to Lyman County's 90 nights. Tripp County, SD, 61 km south, gets 75 nights.
| County | Distance | Below 32°F | Below 20°F | Jan low |
|---|---|---|---|---|
| Lyman County, SD | - | 166 nights | 90 nights | 9°F |
| Buffalo County, SD | 54 km east | 178 nights | 108 nights | 6°F |
| Hughes County, SD | 55 km north | 180 nights | 106 nights | 5°F |
| Tripp County, SD | 61 km south | 148 nights | 75 nights | 13°F |
| Brule County, SD | 63 km east | 163 nights | 88 nights | 10°F |
| Jones County, SD | 68 km west | 157 nights | 83 nights | 12°F |
| Hyde County, SD | 77 km north | 170 nights | 97 nights | 7°F |
Lyman County within SD
Lyman County ranks 42 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 1,696 ft, Lyman County sits 89 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.
Interior pipes have a threshold too: the four freeze points.
Where this comes from
NOAA 1991-2020 climate normals, blended from 3 nearby stations and adjusted for elevation; closest is Kennebec, SD, 2 km away (close 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.