Ice dam risk in Huron, SD
Will your roof get ice dams in Huron, SD?
26.4 dam days a winter
High risk. On an ordinary house in Huron, conditions for an ice dam come on about 26.4 days in a normal winter, mostly in January and December.
Huron averages 44 inches of snow a year and about 75 days with snow on the ground. Snow that lies that long is what turns a little attic heat into a ridge of ice at the eave. 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 Huron
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 12.0 | Moderate |
| Typical, some insulation, not air-sealed | 26.4 | High |
| Older or poorly insulated, warm attic | 44.5 | Severe |
Sealing and insulating a typical attic takes out about 14.5 days a winter here. It drops the risk from high to moderate. An older house with a warm attic should expect closer to 44.5 days.
What to do about ice dams in Huron
- Air-seal the attic floor: the gaps around the hatch, light fixtures, plumbing stacks and the top plates of interior walls. This is the fix that removes the cause, and it usually costs less than a season of contractor ice removal.
- Rake the bottom three or four feet of roof after any storm that leaves more than about six inches, from the ground with a roof rake.
- At the next reroof, ask for ice-and-water membrane under the shingles from the eave to at least 24 inches inside the wall line. It does not stop a dam; it stops the leak when one forms.
Which to spend on first: air sealing or heat cable.
Huron winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 7.8 | 22.1 | 9.1 |
| February | 8.9 | 16.2 | 6.1 |
| March | 6.6 | 10.8 | 2.8 |
| April | 5.5 | 2.6 | 0.3 |
| October | 1.4 | 0.6 | 0.1 |
| November | 5.8 | 5.0 | 1.3 |
| December | 8.4 | 17.6 | 6.7 |
Huron next to nearby towns
Huron ranks 6 of 14 South Dakota cities here for ice-dam days, behind Watertown at 35.4 days.
- Mitchell, SD 45 mi, 26.7 days
- Watertown, SD 64 mi, 35.4 days
- Brookings, SD 70 mi, 31.5 days
- Aberdeen, SD 77 mi, 30.2 days
- Sioux Falls, SD 93 mi, 25.5 days
Where these numbers come from
NOAA 1991–2020 climate normals from Huron Regional Airport, 1.3 miles from Huron. 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.