Calhoun County, Iowa · Rockwell City
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Pipes freeze in Calhoun County on about 69 nights a year, mostly November to March. Older homes, 52% of the stock here, are most at risk.
Basements flood here mostly in August. Calhoun County averages 5.8 days a year with an inch of rain or more.
Sewage backups in Calhoun County spike on heavy-rain days, about 5.8 a year, when sewer mains fill up and water finds the lowest drain.
Roof leaks here come from summer downpours and, with about 94 freeze-thaw days a year, from winter ice dams. Most show up as ceiling stains in the room below.
20% of occupied homes in Calhoun County heat mainly with wood or propane, close to the Iowa county median of 22.1%.
Muggy summer nights, lows of 65°F or more, come about 28 times a year in Calhoun County. Mold after a leak spreads fastest from June through August.
Local risk profile
With 4,798 homes and around 9,803 residents, Calhoun County is 570 square miles of western Iowa. Besides Rockwell City, the county seat, the biggest communities are Lake City, Manson and Twin Lakes. It has some of the oldest housing in the state: the median home went up in 1958.
50/100 Water Damage Risk Index: Elevated Calhoun County ranks 46 of 99 Iowa counties. See the statewide ranking and method.The three factors where Calhoun County ranks highest compared with other Iowa counties.
Calhoun County gets more hard-freeze nights than most of Iowa. In the 2015–2024 record the county logged about 69 nights a year at or below 20°F (26th of 99) and 143 below freezing. Twenty degrees is roughly where uninsulated pipes start to freeze.
Cold snaps are the real risk. The worst in the record lasted 19 days below freezing (ending February 2019), and the low bottomed out near -25°F on January 30, 2019.
Most freezing nights fall from November to March, peaking in January. Disconnect garden hoses and shut off outdoor spigots before the first hard frost, and keep the heat at 55°F or higher if you'll be away.
Freezing nights typically start around Oct 16 and end around Apr 25.
Calhoun gets fewer downpours than most Iowa counties, but they still fill basements. About 5.8 days a year bring an inch or more (92nd of 99), most often in August, out of 31.9 inches of total precipitation. On August 20, 2018, 2.72 inches fell in a single day. The worst three-day stretch dropped 4.34 inches, ending August 21, 2018, the kind of soaking that overwhelms sump pumps and storm sewers.
About 94 days a year swing from below freezing at night to above freezing by day. Those freeze-thaw cycles feed ice dams on roofs, open cracks in foundations and driveways, and stress pipes that are already marginal.
Housing
81% of homes in Calhoun County predate 1980, above the Iowa county median of 72.8%, which ranks 15th of Iowa's 99 counties.
Older and newer homes sit side by side here: 52% predate 1960 and 8% are from 2000 or later. Corroded pipe is the typical failure in the first group, burst supply hoses in the second.
The Census counted 17% of homes as vacant, above the Iowa county median of 9.5%. Empty houses are where a small leak turns into a large claim, because nobody is there to hear it.
Beyond water
Calhoun County averages 28 warm, muggy nights a year (lows of 65°F or more) and gets the most rain in May. Keep indoor humidity under 60%, as the EPA advises, and dry any leak within 24 to 48 hours; in a humid month a wet basement left alone won't dry by itself.
Mold remediation: what to expectHeating fuel matters for fire risk. In Calhoun County it's 54% utility gas, 24% electric, 20% propane and under 1% wood. Heating equipment, cooking and electrical failures cause most home fires nationally. Even a small kitchen fire can leave soot through the whole house, because smoke follows air currents into closets, ducts and attic space.
Fire and smoke cleanup: first stepsCoverage
Calls connect to restoration companies that work across Calhoun County. The largest communities by population:
Population from ACS 2020-2024 5-year estimates. Townships and unincorporated areas are covered too.
Nearby
Pocahontas gets more pipe-freeze nights than Calhoun. Pocahontas County has the oldest housing nearby, with 86% of homes built before 1980.
By the numbers
| Factor | Calhoun | Iowa median | Rank |
|---|---|---|---|
| Homes built before 1960 | 52% | 48% | 35 of 99 |
| Homes built before 1980 | 81% | 73% | 15 of 99 |
| Homes built 2000 or later | 7.6% | 13% | 93 of 99 |
| Manufactured or mobile homes | 1.5% | 3.2% | 89 of 99 |
| Vacant homes | 17% | 9.5% | 9 of 99 |
| Wood or propane heat | 20% | 22% | 63 of 99 |
| Nights at 20°F or colder | 69/yr | 62/yr | 26 of 99 |
| Days with 1 inch+ of rain | 5.8/yr | 7.1/yr | 92 of 99 |
| Freeze-thaw days | 94/yr | 94/yr | 42 of 99 |
| Muggy nights (65°F+) | 28/yr | 29/yr | 53 of 99 |
Rank 1 is the highest value. Bars run from the lowest to the highest Iowa county; the tick marks the median; orange means higher water damage risk than the median, green means lower.
Questions
Peak risk months in Calhoun County: freezing from November to March, heavy rain in May, July and August.
Sources: U.S. Census Bureau, ACS 2024 5-year estimates (2020-2024); weather from NOAA nClimGrid-Daily county averages (EpiNOAA), 2015–2024, averaged across the county; county boundaries from Census TIGER. Reviewed 2026-10-21. Methodology