Ice dam risk in Watertown, NY
Will your roof get ice dams in Watertown, NY?
29.7 dam days a winter
High risk. On an ordinary house in Watertown, conditions for an ice dam come on about 29.7 days in a normal winter, mostly in January and February.
Watertown averages 116 inches of snow a year and about 92 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 Watertown
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 13.9 | Moderate |
| Typical, some insulation, not air-sealed | 29.7 | High |
| Older or poorly insulated, warm attic | 49.5 | Severe |
Sealing and insulating a typical attic takes out about 15.8 days a winter here. It drops the risk from high to moderate. An older house with a warm attic should expect closer to 49.5 days.
Preventing ice dams on a Watertown 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.
Watertown winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 34.0 | 26.0 | 9.8 |
| February | 29.6 | 25.1 | 9.1 |
| March | 13.6 | 15.7 | 4.2 |
| April | 2.7 | 1.9 | 0.2 |
| October | 0.5 | 0.1 | 0.0 |
| November | 9.1 | 5.1 | 0.8 |
| December | 26.9 | 18.1 | 5.6 |
Watertown next to nearby towns
Watertown ranks 3 of 90 New York cities here for ice-dam days, behind Utica at 46.1 days.
- Oswego, NY 46 mi, 26.0 days
- Fulton, NY 52 mi, 27.6 days
- Rome, NY 56 mi, 46.1 days
- Oneida, NY 63 mi, 27.3 days
- Syracuse, NY 65 mi, 23.9 days
Where these numbers come from
NOAA 1991–2020 climate normals from Watertown, 1.7 miles from Watertown. 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.