Sioux County, Iowa · Orange City
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With 33% of homes built before 1960 and about 78 hard-freeze nights a year, frozen and split pipes are a leading winter risk in the county.
June brings the most downpours to Sioux County, part of 6.8 heavy-rain days a year. Check the sump first.
Backups often follow heavy rain, which Sioux County gets about 6.8 days a year, when storm water overloads sewer mains and pushes up through the lowest drain in the house.
In Sioux County, 4.01 inches fell on the wettest day of the 2015–2024 record. Storms like that, and ice dams in snowy winters, cause most roof leaks.
11% of occupied homes in Sioux County heat mainly with wood or propane, below the Iowa county median of 22.1%.
Muggy summer nights, lows of 65°F or more, come about 23 times a year in Sioux County. Mold after a leak spreads fastest from June through August.
Local risk profile
About 36,212 people live in Sioux County, 768 square miles in northwest Iowa, in roughly 13,285 homes. Besides Orange City, the county seat, the biggest communities are Sioux Center, Rock Valley and Hawarden. Half the homes here were built before 1973, half after.
45/100 Water Damage Risk Index: Elevated Sioux County ranks 65 of 99 Iowa counties. See the statewide ranking and method.The three factors where Sioux County ranks highest compared with other Iowa counties.
Sioux County gets more hard-freeze nights than most of Iowa. It averaged 154 freezing nights a year over 2015–2024, 78 of them at 20°F or colder, cold enough for pipes in outside walls and crawl spaces to freeze. Among 99 Iowa counties that's 5th.
On February 16, 2021 the low fell to about -27°F, and in the stretch ending March 2019 the county went 32 days in a row below freezing. Leaks from split pipes typically appear the day the thaw arrives.
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 12 and end around Apr 25.
Rainfall is about average for Iowa. The county gets about 31 inches of rain and melted snow a year, with 6.8 days of an inch or more (61st of 99). Those downpours cluster in May, June and August, when sump pumps and gutters are tested hardest. The wettest day on record brought 4.01 inches on June 21, 2018. The worst three-day stretch dropped 6 inches, ending June 22, 2024, the kind of soaking that overwhelms sump pumps and storm sewers.
Freeze-thaw days, below freezing overnight and above it by afternoon, come about 97 times a year here. They're the main driver of ice dams and of water working its way through foundation cracks in late winter.
Housing
Iowa's 99 counties range widely in housing age; Sioux ranks 85th, with 63% of its homes built before 1980.
22% of homes were built in 2000 or later, more than in most of Iowa. Newer plumbing rarely corrodes, so damage here tends to come from appliance supply lines, water heaters, sump pumps and storms.
Beyond water
About 23 nights a year in Sioux County stay at 65°F or warmer, a sign of muggy summer air (70th of 99 counties). June is the wettest month. Mold grows when indoor humidity stays above about 60%, the EPA's ceiling. A basement dehumidifier set to 50% and drying anything wet within 24 to 48 hours prevents most problems.
Mold remediation: what to expectHeating fuel matters for fire risk. In Sioux County it's 47% utility gas, 40% electric, 10% 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 Sioux County. The largest communities by population:
Population from ACS 2020-2024 5-year estimates. Townships and unincorporated areas are covered too.
Nearby
Lyon gets more pipe-freeze nights than Sioux. O'Brien County has the oldest housing nearby, with 74% of homes built before 1980.
By the numbers
| Factor | Sioux | Iowa median | Rank |
|---|---|---|---|
| Homes built before 1960 | 33% | 48% | 89 of 99 |
| Homes built before 1980 | 63% | 73% | 85 of 99 |
| Homes built 2000 or later | 22% | 13% | 9 of 99 |
| Manufactured or mobile homes | 1.8% | 3.2% | 76 of 99 |
| Vacant homes | 4.5% | 9.5% | 99 of 99 |
| Wood or propane heat | 11% | 22% | 89 of 99 |
| Nights at 20°F or colder | 78/yr | 62/yr | 5 of 99 |
| Days with 1 inch+ of rain | 6.8/yr | 7.1/yr | 61 of 99 |
| Freeze-thaw days | 97/yr | 94/yr | 11 of 99 |
| Muggy nights (65°F+) | 23/yr | 29/yr | 70 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 Sioux County: freezing from November to March, heavy rain in May, June 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