Lehigh County, Pennsylvania · Allentown
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Pipes freeze in Lehigh County on about 32 nights a year, mostly November to March. Older homes, 42% of the stock here, are most at risk.
April brings the most downpours to Lehigh County, part of 11 heavy-rain days a year. Check the sump first.
Sewage backups in Lehigh County spike on heavy-rain days, about 11 a year, when sewer mains fill up and water finds the lowest drain.
Lehigh County's wettest day in the 2015–2024 record brought 4.67 inches, and about 97 freeze-thaw days a year mean ice dams in some winters.
5% of occupied homes in Lehigh County heat mainly with wood or propane, below the Pennsylvania county median of 10%.
Muggy summer nights, lows of 65°F or more, come about 35 times a year in Lehigh County. Mold after a leak spreads fastest from June through August.
Local risk profile
About 378,792 people live in Lehigh County, 345 square miles in southeast Pennsylvania, in roughly 151,220 homes. The county seat is Allentown, and Fullerton, Emmaus and Ancient Oaks round out the largest towns. The county's median home was built in 1968.
61/100 Water Damage Risk Index: Elevated Lehigh County ranks 12 of 67 Pennsylvania counties. See the statewide ranking and method.The three factors where Lehigh County ranks highest compared with other Pennsylvania counties.
For frozen pipes, Lehigh County is a typical Pennsylvania county, which is still plenty. From 2015–2024 it averaged 32 nights a year at 20°F or colder, the range where pipes in exterior walls, crawl spaces and unheated garages freeze, and 111 nights at or below 32°F. That ranks 43rd of 67 counties.
On February 24, 2015 the low fell to about -7°F, and in the stretch ending January 2018 the county went 14 days in a row below freezing. Leaks from split pipes typically appear the day the thaw arrives.
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 19.
Heavy rain is a bigger factor here than in most of Pennsylvania. Of roughly 49.4 inches of yearly precipitation, the damage comes from the 11 days a year with an inch or more, ranked 3rd of 67. April, August and September see the most. The single wettest day in the record: 4.67 inches, September 2, 2021. Multi-day storms matter most for basements; the wettest three days on record here totaled 5.84 inches (through August 5, 2020).
The temperature crosses 32°F in both directions on roughly 97 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
Pennsylvania's 67 counties range widely in housing age; Lehigh ranks 37th, with 65% of its homes built before 1980.
17% of homes were built in 2000 or later, more than in most of Pennsylvania. Newer plumbing rarely corrodes, so damage here tends to come from appliance supply lines, water heaters, sump pumps and storms.
Renters occupy 34% 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
About 35 nights a year in Lehigh County stay at 65°F or warmer, a sign of muggy summer air (14th of 67 counties). August is the wettest month. 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 Lehigh County it's 35% utility gas, 41% electric, 3% propane and 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 Lehigh County. The largest communities by population:
Population from ACS 2020-2024 5-year estimates. Townships and unincorporated areas are covered too.
Nearby
Carbon, Northampton and Schuylkill get more pipe-freeze nights than Lehigh. Schuylkill County has the oldest housing nearby, with 79% of homes built before 1980.
By the numbers
| Factor | Lehigh | Pennsylvania median | Rank |
|---|---|---|---|
| Homes built before 1960 | 42% | 42% | 34 of 67 |
| Homes built before 1980 | 65% | 66% | 37 of 67 |
| Homes built 2000 or later | 17% | 13% | 19 of 67 |
| Manufactured or mobile homes | 1.7% | 6.6% | 63 of 67 |
| Vacant homes | 4.5% | 12% | 60 of 67 |
| Wood or propane heat | 4.6% | 10% | 62 of 67 |
| Nights at 20°F or colder | 32/yr | 37/yr | 43 of 67 |
| Days with 1 inch+ of rain | 11/yr | 7/yr | 3 of 67 |
| Freeze-thaw days | 97/yr | 98/yr | 39 of 67 |
| Muggy nights (65°F+) | 35/yr | 16/yr | 14 of 67 |
Rank 1 is the highest value. Bars run from the lowest to the highest Pennsylvania county; the tick marks the median; orange means higher water damage risk than the median, green means lower.
Questions
Peak risk months in Lehigh County: freezing from November to March, heavy rain in April, 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