Will Pipes Freeze in Rock County, MN? 94 nights a Year
Freeze nights in Rock County
In a normal year Rock County, MN gets 94 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 89% 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 | 165 nights |
| Bare pipe in garage, attic or outside wall | 20°F | 94 nights |
| Insulated pipe in unheated space | 10°F | 53 nights |
| Inside the heated house | 0°F | 27 nights |
Foam-sleeving a bare pipe in unheated space takes it from 94 nights of risk to 53 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 04/03.
How cold Rock County nights get
Average winter (Dec-Feb) low: 10°F; the coldest month, January, averages 7°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: 53 nights a year, and 27 nights below zero.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 7°F | 11°F | 23°F | 34°F | 47°F | 58°F | 62°F | 59°F | 50°F | 37°F | 23°F | 12°F |
Rock County next to its neighbours
Lyon County, IA, 32 km south, gets 96 nights below 20°F to Rock County's 94 nights. Minnehaha County, SD, 43 km west, gets 89 nights.
| County | Distance | Below 32°F | Below 20°F | Jan low |
|---|---|---|---|---|
| Rock County, MN | - | 165 nights | 94 nights | 7°F |
| Lyon County, IA | 32 km south | 168 nights | 96 nights | 6°F |
| Pipestone County, MN | 38 km north | 173 nights | 104 nights | 5°F |
| Nobles County, MN | 40 km east | 168 nights | 97 nights | 5°F |
| Minnehaha County, SD | 43 km west | 159 nights | 89 nights | 8°F |
| Moody County, SD | 50 km northwest | 175 nights | 103 nights | 4°F |
| Murray County, MN | 56 km northeast | 168 nights | 97 nights | 4°F |
Rock County within MN
Rock County ranks 66 of 87 MN counties for nights below 20°F. The most is St. Louis County, MN at 130 nights, with a 0°F average winter low. The fewest is Winona County, MN: 81 nights, winter lows near 12°F. At 1,522 ft, Rock County sits 407 ft above the state's median county elevation of 1,114 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 Sioux Falls (14 mi NNE), SD, 30 km away (fair match). A normal year, not tonight's forecast: check the forecast low for the night itself. What a "fair" or "distant" station match means is in the method guide.