Ice dam risk in New York, NY
Ice dams in New York, NY: how often
3.2 dam days a winter
Low risk. On an ordinary house in New York, conditions for an ice dam come on about 3.2 days in a normal winter, mostly in February and January.
New York averages 25 inches of snow a year and about 19 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 New York
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 2.2 | Low |
| Typical, some insulation, not air-sealed | 3.2 | Low |
| Older or poorly insulated, warm attic | 4.5 | Low |
The attic matters less in New York than in colder towns: there are only 1.0 day a winter between a typical attic and a sealed one.
What to do about ice dams in New York
- Check the gutters before the first snow and clear them, so meltwater has somewhere to go. If you see icicles thicker than a finger along the eave after a storm, that is the early sign to look at the attic.
Snowy places are not always the worst: why snowfall misleads.
New York winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 6.5 | 5.9 | 1.3 |
| February | 8.5 | 6.9 | 1.3 |
| March | 4.4 | 3.6 | 0.3 |
| April | 0.6 | 0.3 | 0.0 |
| November | 0.2 | 0.1 | 0.0 |
| December | 4.3 | 2.1 | 0.3 |
New York next to nearby towns
New York ranks 90 of 90 New York cities here for ice-dam days, behind Utica at 46.1 days.
- Hoboken, NJ 7 mi, 4.3 days
- Jersey City, NJ 7 mi, 4.7 days
- Union City, NJ 9 mi, 4.3 days
- Bayonne, NJ 9 mi, 4.2 days
- West New York, NJ 9 mi, 4.3 days
Where these numbers come from
NOAA 1991–2020 climate normals from Ny Ave V Brooklyn, 5.2 miles from New 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.