Ice dam risk in New London, CT
Will your roof get ice dams in New London, CT?
4.8 dam days a winter
Low risk. On an ordinary house in New London, conditions for an ice dam come on about 4.8 days in a normal winter, mostly in January and February.
New London averages 25 inches of snow a year and about 21 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 London
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 3.4 | Low |
| Typical, some insulation, not air-sealed | 4.8 | Low |
| Older or poorly insulated, warm attic | 6.6 | Moderate |
The attic matters less in New London than in colder towns: there are only 1.4 days a winter between a typical attic and a sealed one.
Preventing ice dams on a New London roof
- 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 London winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 5.8 | 7.4 | 2.0 |
| February | 8.3 | 6.7 | 1.6 |
| March | 3.9 | 2.9 | 0.4 |
| April | 0.8 | 0.2 | 0.0 |
| November | 0.5 | 0.2 | 0.0 |
| December | 5.2 | 3.7 | 0.7 |
New London next to nearby towns
New London ranks 20 of 21 Connecticut cities here for ice-dam days, behind Torrington at 23.6 days.
- Groton, CT 2 mi, 4.8 days
- Norwich, CT 15 mi, 7.5 days
- Middletown, CT 33 mi, 11.7 days
- Meriden, CT 39 mi, 11.7 days
- Newport, RI 41 mi, 6.3 days
Where these numbers come from
NOAA 1991–2020 climate normals from Groton, 3.3 miles from New London. 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.