Ice dam risk in Portsmouth, VA
How often ice dams form in Portsmouth
0.1 dam days a winter
Almost never. An ordinary house in Portsmouth sees 0.1 days a winter when an ice dam can form, because snow rarely stays on a roof long enough below freezing.
Portsmouth averages 3 inches of snow a year and about 1 day with snow on the ground. Too little lies on the roof for long. The conditions that make a dam need all three at once: snow, cold at the eave and heat above it.
Do you need to do anything in Portsmouth?
- Nothing for ice dams. If you are buying here and an inspector mentions water at the eaves, ask what they saw: it is far more likely a gutter, flashing or drip-edge problem than ice.
Snowy places are not always the worst: why snowfall misleads.
Portsmouth winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 2.3 | 1.0 | 0.1 |
| February | 0.7 | 0.4 | 0.0 |
Portsmouth next to nearby towns
Portsmouth ranks 36 of 39 Virginia cities here for ice-dam days, behind Winchester at 4.7 days.
- Norfolk, VA 8 mi, 0.1 days
- Chesapeake, VA 13 mi, 0.4 days
- Hampton, VA 13 mi, 0.4 days
- Newport News, VA 18 mi, 0.4 days
- Poquoson, VA 19 mi, 0.4 days
Where these numbers come from
NOAA 1991–2020 climate normals from Norfolk Nas, 6.6 miles from Portsmouth. 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.