Will Pipes Freeze in Jefferson County, ID? 107 nights a Year
Freeze nights in Jefferson County
In a normal year Jefferson County, ID gets 107 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 94% 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 | 199 nights |
| Bare pipe in garage, attic or outside wall | 20°F | 107 nights |
| Insulated pipe in unheated space | 10°F | 55 nights |
| Inside the heated house | 0°F | 26 nights |
Foam-sleeving a bare pipe in unheated space takes it from 107 nights of risk to 55 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 09/11, last around 06/03. For 20°F: 10/15 to 04/18.
How cold Jefferson County nights get
Average winter (Dec-Feb) low: 10°F; the coldest month, January, averages 8°F overnight. 10 months normally bring at least one night below 32°F (Jan, Feb, Mar, Apr, May, Jun, 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: 55 nights a year, and 26 nights below zero.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 8°F | 12°F | 22°F | 29°F | 38°F | 44°F | 50°F | 48°F | 40°F | 29°F | 19°F | 10°F |
Jefferson County next to its neighbours
Fremont County, ID, 82 km northeast, gets 121 nights below 20°F to Jefferson County's 107 nights. Madison County, ID, 53 km east, gets 88 nights.
| County | Distance | Below 32°F | Below 20°F | Jan low |
|---|---|---|---|---|
| Jefferson County, ID | - | 199 nights | 107 nights | 8°F |
| Madison County, ID | 53 km east | 186 nights | 88 nights | 12°F |
| Clark County, ID | 55 km north | 189 nights | 102 nights | 12°F |
| Bingham County, ID | 65 km south | 164 nights | 66 nights | 17°F |
| Butte County, ID | 70 km west | 189 nights | 100 nights | 9°F |
| Bonneville County, ID | 72 km southeast | 196 nights | 91 nights | 14°F |
| Fremont County, ID | 82 km northeast | 231 nights | 121 nights | 8°F |
Jefferson County within ID
Jefferson County ranks 9 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 4,794 ft, Jefferson County sits 148 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.
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 Hamer (4 mi NW), ID, 19 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.