Ice dam risk in Annapolis, MD
How often ice dams form in Annapolis
3.0 dam days a winter
Low risk. On an ordinary house in Annapolis, conditions for an ice dam come on about 3.0 days in a normal winter, mostly in February and January.
Annapolis averages 16 inches of snow a year and about 14 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 Annapolis
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 2.5 | Low |
| Typical, some insulation, not air-sealed | 3.0 | Low |
| Older or poorly insulated, warm attic | 3.6 | Low |
The attic matters less in Annapolis than in colder towns: there are only 0.5 days a winter between a typical attic and a sealed one.
What to do about ice dams in Annapolis
- 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.
Annapolis winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 5.7 | 4.0 | 1.0 |
| February | 6.3 | 6.3 | 1.4 |
| March | 1.7 | 1.6 | 0.2 |
| December | 2.2 | 2.2 | 0.4 |
Annapolis next to nearby towns
Annapolis ranks 11 of 23 Maryland cities here for ice-dam days, behind Hagerstown at 12.1 days.
- Bowie, MD 13 mi, 3.0 days
- New Carrollton, MD 20 mi, 2.9 days
- Greenbelt, MD 20 mi, 2.9 days
- Laurel, MD 21 mi, 2.9 days
- College Park, MD 23 mi, 2.9 days
Where these numbers come from
NOAA 1991–2020 climate normals from Upper Marlboro 3 NNW, 16.4 miles from Annapolis. 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.