Delaware County, Ohio · Delaware
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Delaware County averages 32 nights a year at 20°F or colder, mostly November to March, and 10% of its homes predate 1960.
Heavy rain days of an inch or more come about 5.6 times a year here, most often in March. A sump pump that hasn't run since last season is a common weak point.
10% of homes here predate 1960, when clay and cast iron sewer laterals were standard. Roots and cracks in those lines are a common cause of backups.
In Delaware County, 3.28 inches fell on the wettest day of the 2015–2024 record. Storms like that, and ice dams in snowy winters, cause most roof leaks.
6% of occupied homes in Delaware County heat mainly with wood or propane, below the Ohio county median of 15.9%.
About 37 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 86,269 homes and around 226,834 residents, Delaware County is 443 square miles of central Ohio. The county seat is Delaware, and Powell, Sunbury and Galena round out the largest towns. Much of its housing is recent, with a median build year of 2000.
38/100 Water Damage Risk Index: Moderate Delaware County ranks 71 of 88 Ohio counties. See the statewide ranking and method.The three factors where Delaware County ranks highest compared with other Ohio counties.
For frozen pipes, Delaware County is a typical Ohio county, which is still plenty. In the 2015–2024 record the county logged about 32 nights a year at or below 20°F (35th of 88) and 107 below freezing. Twenty degrees is roughly where uninsulated pipes start to freeze.
Cold snaps are the real risk. The worst in the record lasted 16 days below freezing (ending February 2021), and the low bottomed out near -9°F on February 24, 2015.
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 27 and the last spring freeze around Apr 20.
Rainfall is about average for Ohio. About 5.6 days a year bring an inch or more (46th of 88), most often in March, out of 42 inches of total precipitation. On June 23, 2016, 3.28 inches fell in a single day. Multi-day storms matter most for basements; the wettest three days on record here totaled 4.16 inches (through September 10, 2018).
The temperature crosses 32°F in both directions on roughly 83 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
Ohio's 88 counties range widely in housing age; Delaware ranks 88th, with 20% of its homes built before 1980.
Growth since 2000 added 51% of today's homes. In houses that new, the weak points are washing machine hoses, ice maker lines, water heaters and sump pumps rather than the pipes in the walls.
About 30% of homes went up between 1980 and 1999. Some houses from the late 1970s to the mid-1990s were plumbed with polybutylene, a gray plastic pipe known for failing at fittings. A plumber can tell you in a few minutes whether you have it.
Beyond water
About 37 nights a year in Delaware County stay at 65°F or warmer, a sign of muggy summer air (32nd of 88 counties). June 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, Delaware County homes break down as 68% utility gas, 24% electric, 6% 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 Delaware County. The largest communities by population:
Population from ACS 2020-2024 5-year estimates. Townships and unincorporated areas are covered too.
Nearby
Knox, Marion, Morrow and Union get more pipe-freeze nights than Delaware. Marion County has the oldest housing nearby, with 74% of homes built before 1980.
By the numbers
| Factor | Delaware | Ohio median | Rank |
|---|---|---|---|
| Homes built before 1960 | 10% | 37% | 88 of 88 |
| Homes built before 1980 | 20% | 61% | 88 of 88 |
| Homes built 2000 or later | 51% | 17% | 1 of 88 |
| Manufactured or mobile homes | 2% | 5.9% | 76 of 88 |
| Vacant homes | 4.6% | 8.4% | 83 of 88 |
| Wood or propane heat | 6.2% | 16% | 72 of 88 |
| Nights at 20°F or colder | 32/yr | 31/yr | 35 of 88 |
| Days with 1 inch+ of rain | 5.6/yr | 5.7/yr | 46 of 88 |
| Freeze-thaw days | 83/yr | 82/yr | 38 of 88 |
| Muggy nights (65°F+) | 37/yr | 35/yr | 32 of 88 |
Rank 1 is the highest value. Bars run from the lowest to the highest Ohio county; the tick marks the median; orange means higher water damage risk than the median, green means lower.
Questions
Peak risk months in Delaware County: freezing from November to March, heavy rain in March, June 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