Will Pipes Freeze in Custer County, MT? 97 nights a Year
Freeze nights in Custer County
In a normal year Custer County, MT gets 97 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 91% 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 | 180 nights |
| Bare pipe in garage, attic or outside wall | 20°F | 97 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 97 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 09/15, last around 05/22. For 20°F: 10/13 to 04/18.
How cold Custer County nights get
Average winter (Dec-Feb) low: 10°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, April, October, November, December: 53 nights a year, and 27 nights below zero.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 8°F | 12°F | 22°F | 32°F | 42°F | 51°F | 57°F | 55°F | 45°F | 32°F | 20°F | 10°F |
Custer County next to its neighbours
Prairie County, MT, 61 km north, gets 105 nights below 20°F to Custer County's 97 nights. Rosebud County, MT, 86 km west, gets 84 nights.
| County | Distance | Below 32°F | Below 20°F | Jan low |
|---|---|---|---|---|
| Custer County, MT | - | 180 nights | 97 nights | 8°F |
| Prairie County, MT | 61 km north | 188 nights | 105 nights | 6°F |
| Rosebud County, MT | 86 km west | 172 nights | 84 nights | 11°F |
| Fallon County, MT | 88 km east | 185 nights | 103 nights | 7°F |
| Powder River County, MT | 95 km south | 186 nights | 97 nights | 11°F |
| Carter County, MT | 115 km southeast | 184 nights | 104 nights | 7°F |
| Dawson County, MT | 122 km northeast | 175 nights | 94 nights | 8°F |
Custer County within MT
Custer County ranks 28 of 56 MT counties for nights below 20°F. The most is Sheridan County, MT at 129 nights, with a 2°F average winter low. The fewest is Lake County, MT: 40 nights, winter lows near 22°F. At 2,898 ft, Custer County sits 1,024 ft below the state's median county elevation of 3,922 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 Mizpah (4 mi NNW), MT, 20 km away (fair match). A normal year, not tonight's forecast: check the forecast low for the night itself. How a county figure is built from stations: how the numbers are made.