Ice dam risk in Oswego, NY
Ice dams in Oswego, NY: how often
26.0 dam days a winter
High risk. On an ordinary house in Oswego, conditions for an ice dam come on about 26.0 days in a normal winter, mostly in January and February.
Oswego averages 140 inches of snow a year and about 89 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 Oswego
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 12.4 | Moderate |
| Typical, some insulation, not air-sealed | 26.0 | High |
| Older or poorly insulated, warm attic | 43.1 | Severe |
Sealing and insulating a typical attic takes out about 13.7 days a winter here. It drops the risk from high to moderate. An older house with a warm attic should expect closer to 43.1 days.
Preventing ice dams on a Oswego 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.
Oswego winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 44.7 | 24.4 | 8.7 |
| February | 35.3 | 24.1 | 8.2 |
| March | 17.1 | 17.2 | 3.9 |
| April | 2.8 | 1.4 | 0.1 |
| October | 0.2 | 0.0 | 0.0 |
| November | 9.4 | 5.0 | 0.5 |
| December | 30.6 | 16.7 | 4.5 |
Oswego next to nearby towns
Oswego ranks 12 of 90 New York cities here for ice-dam days, behind Utica at 46.1 days.
- Fulton, NY 10 mi, 27.6 days
- Syracuse, NY 34 mi, 23.9 days
- Auburn, NY 36 mi, 26.1 days
- Watertown, NY 46 mi, 29.7 days
- Geneva, NY 48 mi, 24.0 days
Where these numbers come from
NOAA 1991–2020 climate normals from Oswego, 1.8 miles from Oswego. 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.