Will Pipes Freeze in Yellowstone County, MT? 89 nights a Year
Freeze nights in Yellowstone County
In a normal year Yellowstone County, MT gets 89 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 87% of US counties.
Risk level: Severe. The risk season runs October to April, worst in December.
It depends where the pipe is
| Pipe | Freezes near | Nights a year |
|---|---|---|
| Outdoor spigot, open crawlspace | 32°F | 181 nights |
| Bare pipe in garage, attic or outside wall | 20°F | 89 nights |
| Insulated pipe in unheated space | 10°F | 44 nights |
| Inside the heated house | 0°F | 20 nights |
Foam-sleeving a bare pipe in unheated space takes it from 89 nights of risk to 44 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 09/25, last around 05/12. For 20°F: 10/26 to 04/06.
How cold Yellowstone County nights get
Average winter (Dec-Feb) low: 13°F; the coldest month, January, averages 12°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, October, November, December: 44 nights a year, and 20 nights below zero.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 12°F | 14°F | 22°F | 32°F | 41°F | 50°F | 55°F | 53°F | 43°F | 31°F | 21°F | 13°F |
Yellowstone County next to its neighbours
Carbon County, MT, 98 km southwest, gets 91 nights below 20°F to Yellowstone County's 89 nights. Musselshell County, MT, 64 km north, gets 76 nights.
| County | Distance | Below 32°F | Below 20°F | Jan low |
|---|---|---|---|---|
| Yellowstone County, MT | - | 181 nights | 89 nights | 12°F |
| Musselshell County, MT | 64 km north | 169 nights | 76 nights | 13°F |
| Big Horn County, MT | 83 km southeast | 175 nights | 88 nights | 13°F |
| Treasure County, MT | 84 km northeast | 173 nights | 85 nights | 10°F |
| Golden Valley County, MT | 85 km northwest | 181 nights | 87 nights | 14°F |
| Stillwater County, MT | 91 km west | 182 nights | 87 nights | 11°F |
| Carbon County, MT | 98 km southwest | 183 nights | 91 nights | 11°F |
Yellowstone County within MT
Yellowstone County ranks 34 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 2,990 ft, Yellowstone County sits 933 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 Huntley Experiment Station, MT, 3 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.