Woodbury County, Iowa · Sioux City
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Pipes freeze in Woodbury County on about 67 nights a year, mostly November to March. Older homes, 51% of the stock here, are most at risk.
Basements flood here mostly in August. Woodbury County averages 5.9 days a year with an inch of rain or more.
Backups often follow heavy rain, which Woodbury County gets about 5.9 days a year, when storm water overloads sewer mains and pushes up through the lowest drain in the house.
Roof leaks here come from summer downpours and, with about 97 freeze-thaw days a year, from winter ice dams. Most show up as ceiling stains in the room below.
6% of occupied homes in Woodbury County heat mainly with wood or propane, below the Iowa county median of 22.1%.
With 30 muggy nights a year, mold in Woodbury County can appear within days of a leak. Dry first, then clean.
Local risk profile
Woodbury County covers 873 square miles of western Iowa, with about 106,247 residents and 43,388 homes. Besides Sioux City, the county seat, the biggest communities are Sergeant Bluff, Moville and Sloan. It has some of the oldest housing in the state: the median home went up in 1959.
49/100 Water Damage Risk Index: Elevated Woodbury County ranks 52 of 99 Iowa counties. See the statewide ranking and method.The three factors where Woodbury County ranks highest compared with other Iowa counties.
For frozen pipes, Woodbury County is a typical Iowa county, which is still plenty. In the 2015–2024 record the county logged about 67 nights a year at or below 20°F (34th of 99) and 144 below freezing. Twenty degrees is roughly where uninsulated pipes start to freeze.
Cold snaps are the real risk. The worst in the record lasted 32 days below freezing (ending March 2019), and the low bottomed out near -28°F on February 16, 2021.
The freeze season here runs November to March, with January the coldest. If you travel then, leave the thermostat at 55°F or above and open sink cabinets on outside walls.
On average the first fall freeze arrives around Oct 14 and the last spring freeze around Apr 24.
Woodbury gets fewer downpours than most Iowa counties, but they still fill basements. About 5.9 days a year bring an inch or more (89th of 99), most often in August, out of 29.6 inches of total precipitation. On September 5, 2018, 2.4 inches fell in a single day. Multi-day storms matter most for basements; the wettest three days on record here totaled 3.81 inches (through August 19, 2015).
About 97 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
Iowa's 99 counties range widely in housing age; Woodbury ranks 43rd, with 74% of its homes built before 1980.
The mix runs from 51% built before 1960 to 12% built since 2000, so older neighborhoods bring aging pipe while newer subdivisions bring failed appliance lines and water heaters.
Renters occupy 32% of homes. If you rent, the building is usually the landlord's to repair, but your belongings are only covered by renters insurance.
Beyond water
Summer nights that don't drop below 65°F, a good marker of humid air, come about 30 times a year here, close to the Iowa county median of 29. 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 expectMain heating fuel in Woodbury County's occupied homes: 60% utility gas, 32% electric, 6% propane and under 1% wood. Fires here are likelier to start in the kitchen or the wiring than in the furnace. After any fire, keep the HVAC off until ducts are checked, or soot will travel through the house.
Fire and smoke cleanup: first stepsCoverage
Calls connect to restoration companies that work across Woodbury County. The largest communities by population:
Population from ACS 2020-2024 5-year estimates. Townships and unincorporated areas are covered too.
Nearby
Cherokee, Ida and Plymouth get more pipe-freeze nights than Woodbury. Cherokee County has the oldest housing nearby, with 84% of homes built before 1980.
By the numbers
| Factor | Woodbury | Iowa median | Rank |
|---|---|---|---|
| Homes built before 1960 | 51% | 48% | 37 of 99 |
| Homes built before 1980 | 74% | 73% | 43 of 99 |
| Homes built 2000 or later | 12% | 13% | 57 of 99 |
| Manufactured or mobile homes | 3.5% | 3.2% | 41 of 99 |
| Vacant homes | 6.2% | 9.5% | 89 of 99 |
| Wood or propane heat | 5.8% | 22% | 95 of 99 |
| Nights at 20°F or colder | 67/yr | 62/yr | 34 of 99 |
| Days with 1 inch+ of rain | 5.9/yr | 7.1/yr | 89 of 99 |
| Freeze-thaw days | 97/yr | 94/yr | 11 of 99 |
| Muggy nights (65°F+) | 30/yr | 29/yr | 45 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 Woodbury County: freezing from November to March, heavy rain in May, August and September.
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