Ice dam risk in Dunkirk, NY
Will your roof get ice dams in Dunkirk, NY?
25.0 dam days a winter
High risk. On an ordinary house in Dunkirk, conditions for an ice dam come on about 25.0 days in a normal winter, mostly in February and January.
Dunkirk averages 76 inches of snow a year and about 96 days with snow on the ground. Snow that lies that long is what turns a little attic heat into a ridge of ice at the eave. 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 Dunkirk
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 13.6 | Moderate |
| Typical, some insulation, not air-sealed | 25.0 | High |
| Older or poorly insulated, warm attic | 39.2 | Severe |
Sealing and insulating a typical attic takes out about 11.4 days a winter here. It drops the risk from high to moderate. An older house with a warm attic should expect closer to 39.2 days.
Preventing ice dams on a Dunkirk roof
- Air-seal the attic floor: the gaps around the hatch, light fixtures, plumbing stacks and the top plates of interior walls. This is the fix that removes the cause, and it usually costs less than a season of contractor ice removal.
- 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.
- At the next reroof, ask for ice-and-water membrane under the shingles from the eave to at least 24 inches inside the wall line. It does not stop a dam; it stops the leak when one forms.
Which to spend on first: air sealing or heat cable.
Dunkirk winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 26.7 | 25.3 | 8.0 |
| February | 13.0 | 24.6 | 7.7 |
| March | 11.6 | 18.2 | 3.9 |
| April | 1.4 | 2.4 | 0.2 |
| October | 0.2 | 0.1 | 0.0 |
| November | 5.4 | 5.9 | 0.5 |
| December | 17.3 | 19.4 | 4.6 |
Dunkirk next to nearby towns
Dunkirk ranks 16 of 90 New York cities here for ice-dam days, behind Utica at 46.1 days.
- Jamestown, NY 27 mi, 25.4 days
- Lackawanna, NY 35 mi, 21.2 days
- Buffalo, NY 37 mi, 21.2 days
- Kenmore, NY 41 mi, 21.4 days
- Tonawanda, NY 43 mi, 21.4 days
Where these numbers come from
NOAA 1991–2020 climate normals from Fredonia, 2.4 miles from Dunkirk. 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.
- Snow-on-the-ground counts come from a second, nearby station, because the closest one does not record them.