Columbia County, Wisconsin · Portage
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Columbia County averages 62 nights a year at 20°F or colder, mostly November to March, and 35% of its homes predate 1960.
August brings the most downpours to Columbia County, part of 7.8 heavy-rain days a year. Check the sump first.
Backups often follow heavy rain, which Columbia County gets about 7.8 days a year, when storm water overloads sewer mains and pushes up through the lowest drain in the house.
In Columbia County, 3.41 inches fell on the wettest day of the 2015–2024 record. Storms like that, and ice dams in snowy winters, cause most roof leaks.
24% of occupied homes in Columbia County heat mainly with wood or propane, below the Wisconsin county median of 32.9%.
About 18 nights a year here stay at 65°F or warmer, so basements and crawl spaces can grow mold even without a leak.
Local risk profile
With 26,880 homes and around 58,272 residents, Columbia County is 766 square miles of southern Wisconsin. Besides Portage, the county seat, the biggest communities are Columbus, Lake Wisconsin and Lodi. Half the homes here were built before 1976, half after.
56/100 Water Damage Risk Index: Elevated Columbia County ranks 22 of 72 Wisconsin counties. See the statewide ranking and method.The three factors where Columbia County ranks highest compared with other Wisconsin counties.
Winters here are on the gentler end for Wisconsin, and pipes still freeze. In the 2015–2024 record the county logged about 62 nights a year at or below 20°F (58th of 72) and 144 below freezing. Twenty degrees is roughly where uninsulated pipes start to freeze.
The longest cold spell was straight 17 days without the temperature rising above freezing, ending in January 2018. The coldest night reached about -31°F on January 31, 2019. Burst pipes usually show up when a spell like that breaks and the ice thaws.
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 18 and end around May 3.
Heavy rain is a bigger factor here than in most of Wisconsin. Of roughly 37.9 inches of yearly precipitation, the damage comes from the 7.8 days a year with an inch or more, ranked 16th of 72. June, August and September see the most. The single wettest day in the record: 3.41 inches, October 2, 2019. The worst three-day stretch dropped 5.33 inches, ending August 29, 2018, the kind of soaking that overwhelms sump pumps and storm sewers.
The temperature crosses 32°F in both directions on roughly 93 days a year. Each cycle melts and refreezes water at roof edges and in foundation cracks, which is how ice dams and basement seepage get started.
Housing
55% of homes in Columbia County predate 1980, close to the Wisconsin county median of 54.1%, which ranks 34th of Wisconsin's 72 counties.
Older and newer homes sit side by side here: 35% predate 1960 and 22% are from 2000 or later. Corroded pipe is the typical failure in the first group, burst supply hoses in the second.
The 1980s and 1990s account for 23% of the county's homes. If yours is from those decades, look under the sinks and at the water heater for gray plastic pipe stamped PB, which is polybutylene and leak-prone.
Beyond water
About 18 nights a year in Columbia County stay at 65°F or warmer, a sign of muggy summer air (14th of 72 counties). August is the wettest month. The EPA recommends keeping indoor humidity below 60%, ideally 30 to 50%. Basements can pass 60% on their own in summer, so a dehumidifier matters even without a leak, and anything wet should be dried within 24 to 48 hours.
Mold remediation: what to expectBy main heating fuel, Columbia County homes break down as 57% utility gas, 16% electric, 20% propane and 4% 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 Columbia County. The largest communities by population:
Population from ACS 2020-2024 5-year estimates. Townships and unincorporated areas are covered too.
Nearby
Adams, Dodge, Green Lake, Marquette and Sauk get more pipe-freeze nights than Columbia. Green Lake County has the oldest housing nearby, with 65% of homes built before 1980.
By the numbers
| Factor | Columbia | Wisconsin median | Rank |
|---|---|---|---|
| Homes built before 1960 | 35% | 31% | 25 of 72 |
| Homes built before 1980 | 55% | 54% | 34 of 72 |
| Homes built 2000 or later | 22% | 21% | 35 of 72 |
| Manufactured or mobile homes | 2.7% | 4.8% | 55 of 72 |
| Vacant homes | 10% | 12% | 41 of 72 |
| Wood or propane heat | 24% | 33% | 48 of 72 |
| Nights at 20°F or colder | 62/yr | 73/yr | 58 of 72 |
| Days with 1 inch+ of rain | 7.8/yr | 6.3/yr | 16 of 72 |
| Freeze-thaw days | 93/yr | 94/yr | 38 of 72 |
| Muggy nights (65°F+) | 18/yr | 11/yr | 14 of 72 |
Rank 1 is the highest value. Bars run from the lowest to the highest Wisconsin county; the tick marks the median; orange means higher water damage risk than the median, green means lower.
Questions
Peak risk months in Columbia County: freezing from November to March, heavy rain in June, 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