Ice dam risk in Bristol, VA
How often ice dams form in Bristol
1.2 dam days a winter
Low risk. On an ordinary house in Bristol, conditions for an ice dam come on about 1.2 days in a normal winter, mostly in January and February.
Bristol averages 9 inches of snow a year and about 7 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 Bristol
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 1.0 | Low |
| Typical, some insulation, not air-sealed | 1.2 | Low |
| Older or poorly insulated, warm attic | 1.5 | Low |
The attic matters less in Bristol than in colder towns: there are only 0.2 days a winter between a typical attic and a sealed one.
Preventing ice dams on a Bristol 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.
Bristol winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 3.0 | 2.7 | 0.6 |
| February | 3.0 | 2.1 | 0.4 |
| March | 1.1 | 0.5 | 0.1 |
| April | 0.1 | 0.0 | 0.0 |
| November | 0.3 | 0.3 | 0.0 |
| December | 1.7 | 1.3 | 0.2 |
Bristol next to nearby towns
Bristol ranks 23 of 39 Virginia cities here for ice-dam days, behind Winchester at 4.7 days.
- Bristol, TN 5 mi, 1.2 days
- Elizabethton, TN 20 mi, 1.1 days
- Kingsport, TN 22 mi, 0.6 days
- Johnson City, TN 23 mi, 1.1 days
- Boone, NC 39 mi, 4.9 days
Where these numbers come from
NOAA 1991–2020 climate normals from Bristol Airport, 16.4 miles from Bristol. 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.