Will Pipes Freeze in Jefferson County, WI? 73 nights a Year
Freeze nights in Jefferson County
In a normal year Jefferson County, WI gets 73 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 78% of US counties.
Risk level: Severe. The risk season runs November to April, worst in January.
It depends where the pipe is
| Pipe | Freezes near | Nights a year |
|---|---|---|
| Outdoor spigot, open crawlspace | 32°F | 144 nights |
| Bare pipe in garage, attic or outside wall | 20°F | 73 nights |
| Insulated pipe in unheated space | 10°F | 37 nights |
| Inside the heated house | 0°F | 17 nights |
Foam-sleeving a bare pipe in unheated space takes it from 73 nights of risk to 37 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 10/18, last around 04/25. For 20°F: 11/16 to 03/27.
How cold Jefferson County nights get
Average winter (Dec-Feb) low: 14°F; the coldest month, January, averages 11°F overnight. 8 months normally bring at least one night below 32°F (Jan, Feb, Mar, Apr, May, Oct, Nov, Dec). Nights below 10°F, cold enough to freeze insulated pipe in an unheated space, come in January, February, March, November, December: 37 nights a year, and 17 nights below zero.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 11°F | 14°F | 25°F | 36°F | 48°F | 58°F | 62°F | 61°F | 52°F | 41°F | 29°F | 18°F |
Jefferson County next to its neighbours
Dodge County, WI, 47 km north, gets 81 nights below 20°F to Jefferson County's 73 nights. Waukesha County, WI, 38 km east, gets 71 nights.
| County | Distance | Below 32°F | Below 20°F | Jan low |
|---|---|---|---|---|
| Jefferson County, WI | - | 144 nights | 73 nights | 11°F |
| Waukesha County, WI | 38 km east | 146 nights | 71 nights | 12°F |
| Walworth County, WI | 43 km southeast | 141 nights | 61 nights | 14°F |
| Rock County, WI | 45 km southwest | 147 nights | 71 nights | 11°F |
| Dodge County, WI | 47 km north | 154 nights | 81 nights | 9°F |
| Dane County, WI | 53 km west | 155 nights | 79 nights | 11°F |
| Washington County, WI | 61 km northeast | 157 nights | 79 nights | 10°F |
Jefferson County within WI
Jefferson County ranks 62 of 72 WI counties for nights below 20°F. The most is Vilas County, WI at 116 nights, with a 4°F average winter low. The fewest is Racine County, WI: 55 nights, winter lows near 19°F. At 824 ft, Jefferson County sits 171 ft below the state's median county elevation of 995 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 Jefferson Wastewater Plant, WI, 3 km away (close 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.