Will Pipes Freeze in Dallas County, IA? 72 nights a Year
Freeze nights in Dallas County
In a normal year Dallas County, IA gets 72 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 | 146 nights |
| Bare pipe in garage, attic or outside wall | 20°F | 72 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 72 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 10/10, last around 04/25. For 20°F: 11/08 to 03/27.
How cold Dallas County nights get
Average winter (Dec-Feb) low: 15°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 | 15°F | 27°F | 38°F | 50°F | 61°F | 64°F | 62°F | 53°F | 40°F | 28°F | 17°F |
Dallas County next to its neighbours
Guthrie County, IA, 38 km west, gets 82 nights below 20°F to Dallas County's 72 nights. Polk County, IA, 39 km east, gets 69 nights.
| County | Distance | Below 32°F | Below 20°F | Jan low |
|---|---|---|---|---|
| Dallas County, IA | - | 146 nights | 72 nights | 11°F |
| Guthrie County, IA | 38 km west | 156 nights | 82 nights | 10°F |
| Polk County, IA | 39 km east | 142 nights | 69 nights | 12°F |
| Madison County, IA | 39 km south | 145 nights | 73 nights | 10°F |
| Boone County, IA | 40 km north | 151 nights | 76 nights | 10°F |
| Greene County, IA | 49 km northwest | 149 nights | 75 nights | 9°F |
| Adair County, IA | 54 km southwest | 138 nights | 67 nights | 11°F |
Dallas County within IA
Dallas County ranks 63 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 963 ft, Dallas County sits 127 ft below 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.
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 Perry, IA, 18 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.