Ice dam risk in Marietta, OH
Ice dams in Marietta, OH: how often
3.7 dam days a winter
Low risk. On an ordinary house in Marietta, conditions for an ice dam come on about 3.7 days in a normal winter, mostly in January and February.
Marietta averages 16 inches of snow a year and about 15 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 Marietta
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 2.4 | Low |
| Typical, some insulation, not air-sealed | 3.7 | Low |
| Older or poorly insulated, warm attic | 5.3 | Moderate |
The attic matters less in Marietta than in colder towns: there are only 1.3 days a winter between a typical attic and a sealed one.
Preventing ice dams on a Marietta 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.
Marietta winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 7.2 | 7.1 | 1.9 |
| February | 4.0 | 3.9 | 1.0 |
| March | 2.7 | 1.5 | 0.2 |
| April | 0.1 | 0.0 | 0.0 |
| November | 0.2 | 0.1 | 0.0 |
| December | 2.1 | 2.4 | 0.5 |
Marietta next to nearby towns
Marietta ranks 174 of 176 Ohio cities here for ice-dam days, behind Euclid at 24.8 days.
- Vienna, WV 8 mi, 3.5 days
- Parkersburg, WV 12 mi, 3.5 days
- Athens, OH 36 mi, 5.2 days
- Cambridge, OH 42 mi, 6.5 days
- Zanesville, OH 48 mi, 8.0 days
Where these numbers come from
NOAA 1991–2020 climate normals from Marietta Wwtp, 1.2 miles from Marietta. 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.