Ice dam risk in Harrisonburg, VA
Will your roof get ice dams in Harrisonburg, VA?
4.2 dam days a winter
Low risk. On an ordinary house in Harrisonburg, conditions for an ice dam come on about 4.2 days in a normal winter, mostly in February and January.
Harrisonburg averages 19 inches of snow a year and about 19 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 Harrisonburg
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 3.3 | Low |
| Typical, some insulation, not air-sealed | 4.2 | Low |
| Older or poorly insulated, warm attic | 5.3 | Moderate |
The attic matters less in Harrisonburg than in colder towns: there are only 0.9 days a winter between a typical attic and a sealed one.
Preventing ice dams on a Harrisonburg 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.
Harrisonburg winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 4.2 | 4.6 | 1.2 |
| February | 6.2 | 6.4 | 1.5 |
| March | 4.5 | 2.7 | 0.4 |
| April | 0.1 | 0.0 | 0.0 |
| October | 0.2 | 0.1 | 0.0 |
| November | 0.6 | 0.4 | 0.1 |
| December | 3.6 | 4.3 | 1.0 |
Harrisonburg next to nearby towns
Harrisonburg ranks 7 of 39 Virginia cities here for ice-dam days, behind Winchester at 4.7 days.
- Staunton, VA 22 mi, 3.9 days
- Waynesboro, VA 26 mi, 3.9 days
- Charlottesville, VA 35 mi, 2.3 days
- Culpeper, VA 47 mi, 4.5 days
- Front Royal, VA 50 mi, 3.6 days
Where these numbers come from
NOAA 1991–2020 climate normals from Dale Enterprise, 3.6 miles from Harrisonburg. 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.
- The nearest weather station sits at a noticeably different elevation from Harrisonburg, so the snow figures may run high or low for the town itself.