Will Pipes Freeze in Williamson County, IL? 29 nights a Year
Freeze nights in Williamson County
In a normal year Williamson County, IL gets 29 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 45% of US counties.
Risk level: Regular. The risk season runs November to March, worst in January.
It depends where the pipe is
| Pipe | Freezes near | Nights a year |
|---|---|---|
| Outdoor spigot, open crawlspace | 32°F | 98 nights |
| Bare pipe in garage, attic or outside wall | 20°F | 29 nights |
| Insulated pipe in unheated space | 10°F | 8 nights |
| Inside the heated house | 0°F | 1 night |
Foam-sleeving a bare pipe in unheated space takes it from 29 nights of risk to 8 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 10/22, last around 04/09. For 20°F: 11/27 to 03/06.
How cold Williamson County nights get
Average winter (Dec-Feb) low: 26°F; the coldest month, January, averages 24°F overnight. 7 months normally bring at least one night below 32°F (Jan, Feb, Mar, Apr, Oct, Nov, Dec). Nights below 10°F, cold enough to freeze insulated pipe in an unheated space, come in January, February, December: 8 nights a year, and 1 night below zero.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 24°F | 27°F | 35°F | 45°F | 55°F | 64°F | 68°F | 65°F | 56°F | 45°F | 35°F | 28°F |
Williamson County next to its neighbours
Johnson County, IL, 30 km south, gets 23 nights.
| County | Distance | Below 32°F | Below 20°F | Jan low |
|---|---|---|---|---|
| Williamson County, IL | - | 98 nights | 29 nights | 24°F |
| Franklin County, IL | 29 km north | 95 nights | 29 nights | 24°F |
| Johnson County, IL | 30 km south | 83 nights | 23 nights | 26°F |
| Saline County, IL | 34 km east | 95 nights | 25 nights | 24°F |
| Union County, IL | 39 km southwest | 95 nights | 28 nights | 25°F |
| Jackson County, IL | 40 km west | 96 nights | 27 nights | 24°F |
| Pope County, IL | 49 km southeast | 90 nights | 27 nights | 25°F |
Williamson County within IL
Williamson County ranks 90 of 102 IL counties for nights below 20°F. The most is Jo Daviess County, IL at 76 nights, with a 14°F average winter low. The fewest is Alexander County, IL: 21 nights, winter lows near 29°F. At 432 ft, Williamson County sits 199 ft below the state's median county elevation of 632 ft.
What to do here
- Insulate every pipe in unheated space before the season starts.
- Heat tape on the runs you cannot insulate well.
- Shut off and drain outdoor spigots for the season.
What insulating actually removes here, and when heat tape is needed: insulate or heat tape?.
Where this comes from
NOAA 1991-2020 climate normals, blended from 3 nearby stations and adjusted for elevation; closest is Carbondale Sewage Plt, IL, 21 km away (close 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.