Ice dam risk in Hartford, CT
Ice dams in Hartford, CT: how often
11.2 dam days a winter
Moderate risk. On an ordinary house in Hartford, conditions for an ice dam come on about 11.2 days in a normal winter, mostly in February and January.
Hartford averages 52 inches of snow a year and about 42 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 Hartford
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 7.0 | Moderate |
| Typical, some insulation, not air-sealed | 11.2 | Moderate |
| Older or poorly insulated, warm attic | 16.4 | High |
Sealing and insulating a typical attic takes out about 4.2 days a winter here. It does not move the risk band, but it shortens every dam. An older house with a warm attic should expect closer to 16.4 days.
Preventing ice dams on a Hartford 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.
Which to spend on first: air sealing or heat cable.
Hartford winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 14.2 | 12.5 | 4.0 |
| February | 14.8 | 13.4 | 3.8 |
| March | 9.4 | 8.5 | 1.6 |
| April | 1.1 | 0.2 | 0.0 |
| October | 0.7 | 0.1 | 0.0 |
| November | 1.4 | 0.6 | 0.1 |
| December | 10.1 | 6.5 | 1.7 |
Hartford next to nearby towns
Hartford ranks 9 of 21 Connecticut cities here for ice-dam days, behind Torrington at 23.6 days.
- New Britain, CT 8 mi, 11.7 days
- Bristol, CT 15 mi, 11.7 days
- Middletown, CT 15 mi, 11.7 days
- Meriden, CT 17 mi, 11.7 days
- Agawam Town, MA 21 mi, 16.6 days
Where these numbers come from
NOAA 1991–2020 climate normals from Hartford-Bradley International Airport, 11.9 miles from Hartford. 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.