Ice dam risk in Dover, DE
How often ice dams form in Dover
1.7 dam days a winter
Low risk. On an ordinary house in Dover, conditions for an ice dam come on about 1.7 days in a normal winter, mostly in February and January.
Dover averages 13 inches of snow a year and about 9 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 Dover
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 1.4 | Low |
| Typical, some insulation, not air-sealed | 1.7 | Low |
| Older or poorly insulated, warm attic | 2.1 | Low |
The attic matters less in Dover than in colder towns: there are only 0.3 days a winter between a typical attic and a sealed one.
Preventing ice dams on a Dover 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.
Dover winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 4.1 | 3.1 | 0.7 |
| February | 5.9 | 4.2 | 0.8 |
| March | 0.6 | 0.6 | 0.1 |
| December | 2.6 | 1.5 | 0.2 |
Dover next to nearby towns
Dover ranks 5 of 6 Delaware cities here for ice-dam days, behind Wilmington at 3.6 days.
- Smyrna, DE 10 mi, 1.7 days
- Milford, DE 18 mi, 2.4 days
- Middletown, DE 22 mi, 3.5 days
- Bridgeton, NJ 24 mi, 3.1 days
- Millville, NJ 30 mi, 3.1 days
Where these numbers come from
NOAA 1991–2020 climate normals from Dover, 1.3 miles from Dover. 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.