Ice dam risk in York, PA
Ice dams in York, PA: how often
5.8 dam days a winter
Moderate risk. On an ordinary house in York, conditions for an ice dam come on about 5.8 days in a normal winter, mostly in February and January.
York averages 25 inches of snow a year and about 25 days with snow on the ground. Most of it comes and goes within a few days. The conditions that make a dam need all three at once: snow, cold at the eave and heat above it.
What your attic does to that number in York
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 4.5 | Low |
| Typical, some insulation, not air-sealed | 5.8 | Moderate |
| Older or poorly insulated, warm attic | 7.5 | Moderate |
The attic matters less in York than in colder towns: there are only 1.3 days a winter between a typical attic and a sealed one.
Preventing ice dams on a York roof
- Rake the bottom three or four feet of roof after any storm that leaves more than about six inches, from the ground with a roof rake.
More on when a roof rake is worth it.
York winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 8.5 | 7.8 | 2.1 |
| February | 8.2 | 9.7 | 2.3 |
| March | 3.9 | 2.0 | 0.3 |
| April | 0.2 | 0.0 | 0.0 |
| November | 0.5 | 0.5 | 0.1 |
| December | 3.3 | 5.1 | 1.1 |
York next to nearby towns
York ranks 59 of 68 Pennsylvania cities here for ice-dam days, behind St. Marys at 26.9 days.
- Columbia, PA 13 mi, 6.5 days
- Elizabethtown, PA 15 mi, 6.5 days
- Hanover, PA 17 mi, 7.6 days
- Mechanicsburg, PA 22 mi, 8.0 days
- Harrisburg, PA 23 mi, 8.0 days
Where these numbers come from
NOAA 1991–2020 climate normals from York 3 SSW Pump Station, 3.5 miles from York. A dam day is a day with snow on the roof and freezing at the eave while heat or sun melts the snow above it. This describes a normal winter, not this one.