Will Pipes Freeze in Lemhi County, ID? 135 nights a Year
Freeze nights in Lemhi County
In a normal year Lemhi County, ID gets 135 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 99% of US counties.
Risk level: Severe. The risk season runs September to May, worst in January.
It depends where the pipe is
| Pipe | Freezes near | Nights a year |
|---|---|---|
| Outdoor spigot, open crawlspace | 32°F | 239 nights |
| Bare pipe in garage, attic or outside wall | 20°F | 135 nights |
| Insulated pipe in unheated space | 10°F | 72 nights |
| Inside the heated house | 0°F | 32 nights |
Foam-sleeving a bare pipe in unheated space takes it from 135 nights of risk to 72 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.
How cold Lemhi County nights get
Average winter (Dec-Feb) low: 8°F; the coldest month, January, averages 7°F overnight. 12 months normally bring at least one night below 32°F (Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, 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: 72 nights a year, and 32 nights below zero.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 7°F | 9°F | 18°F | 24°F | 32°F | 38°F | 43°F | 40°F | 34°F | 25°F | 15°F | 7°F |
Lemhi County next to its neighbours
Custer County, ID, 78 km south, gets 145 nights below 20°F to Lemhi County's 135 nights. Beaverhead County, MT, 81 km east, gets 128 nights.
| County | Distance | Below 32°F | Below 20°F | Jan low |
|---|---|---|---|---|
| Lemhi County, ID | - | 239 nights | 135 nights | 7°F |
| Custer County, ID | 78 km south | 261 nights | 145 nights | 3°F |
| Beaverhead County, MT | 81 km east | 228 nights | 128 nights | 9°F |
| Ravalli County, MT | 129 km north | 222 nights | 97 nights | 14°F |
| Valley County, ID | 137 km west | 252 nights | 117 nights | 9°F |
| Clark County, ID | 141 km southeast | 189 nights | 102 nights | 12°F |
| Deer Lodge County, MT | 142 km northeast | 230 nights | 113 nights | 13°F |
Lemhi County within ID
Lemhi County ranks 2 of 44 ID counties for nights below 20°F. The most is Custer County, ID at 145 nights, with a 5°F average winter low. The fewest is Nez Perce County, ID: 20 nights, winter lows near 27°F. At 7,548 ft, Lemhi County sits 2,902 ft above the state's median county elevation of 4,646 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.
At this many nights, foam alone is not the answer: insulate or heat tape?.
Where this comes from
NOAA 1991-2020 climate normals, blended from 3 nearby stations and adjusted for elevation; closest is Jackson, MT, 62 km away (distant 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.