Will Pipes Freeze in Decatur County, IA? 66 nights a Year
Freeze nights in Decatur County
In a normal year Decatur County, IA gets 66 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 74% 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 | 138 nights |
| Bare pipe in garage, attic or outside wall | 20°F | 66 nights |
| Insulated pipe in unheated space | 10°F | 29 nights |
| Inside the heated house | 0°F | 11 nights |
Foam-sleeving a bare pipe in unheated space takes it from 66 nights of risk to 29 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 10/08, last around 04/30. For 20°F: 11/07 to 03/30.
How cold Decatur County nights get
Average winter (Dec-Feb) low: 17°F; the coldest month, January, averages 14°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: 29 nights a year, and 11 nights below zero.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 14°F | 17°F | 29°F | 39°F | 51°F | 61°F | 65°F | 62°F | 53°F | 41°F | 29°F | 19°F |
Decatur County next to its neighbours
Clarke County, IA, 33 km north, gets 72 nights below 20°F to Decatur County's 66 nights. Mercer County, MO, 40 km southeast, gets 56 nights.
| County | Distance | Below 32°F | Below 20°F | Jan low |
|---|---|---|---|---|
| Decatur County, IA | - | 138 nights | 66 nights | 14°F |
| Clarke County, IA | 33 km north | 148 nights | 72 nights | 11°F |
| Wayne County, IA | 38 km east | 141 nights | 69 nights | 13°F |
| Ringgold County, IA | 39 km west | 143 nights | 69 nights | 12°F |
| Mercer County, MO | 40 km southeast | 127 nights | 56 nights | 15°F |
| Harrison County, MO | 47 km south | 132 nights | 59 nights | 15°F |
| Lucas County, IA | 50 km northeast | 153 nights | 79 nights | 11°F |
Decatur County within IA
Decatur County ranks 82 of 99 IA counties for nights below 20°F. The most is Osceola County, IA at 99 nights, with a 8°F average winter low. The fewest is Des Moines County, IA: 52 nights, winter lows near 19°F. At 1,074 ft, Decatur County sits close to the state's median county elevation of 1,090 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.
The dates to be done by: when freeze season starts and ends.
Where this comes from
NOAA 1991-2020 climate normals, blended from 3 nearby stations and adjusted for elevation; closest is Leon (6 mi ESE), IA, 12 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.