Ice dam risk in Port Huron, MI
Will your roof get ice dams in Port Huron, MI?
15.5 dam days a winter
High risk. On an ordinary house in Port Huron, conditions for an ice dam come on about 15.5 days in a normal winter, mostly in January and February.
Port Huron averages 36 inches of snow a year and about 50 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 Port Huron
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 7.4 | Moderate |
| Typical, some insulation, not air-sealed | 15.5 | High |
| Older or poorly insulated, warm attic | 25.7 | High |
Sealing and insulating a typical attic takes out about 8.1 days a winter here. It drops the risk from high to moderate. An older house with a warm attic should expect closer to 25.7 days.
What to do about ice dams in Port 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.
Port Huron winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 11.1 | 17.0 | 6.1 |
| February | 11.4 | 15.6 | 5.3 |
| March | 4.6 | 6.6 | 1.5 |
| April | 0.4 | 0.3 | 0.0 |
| November | 1.3 | 1.2 | 0.1 |
| December | 6.7 | 8.9 | 2.4 |
Port Huron next to nearby towns
Port Huron ranks 61 of 90 Michigan cities here for ice-dam days, behind Sault Ste. Marie at 48.8 days.
- New Baltimore, MI 26 mi, 13.6 days
- Mount Clemens, MI 36 mi, 13.6 days
- Rochester, MI 41 mi, 19.6 days
- Fraser, MI 41 mi, 13.6 days
- Sterling Heights, MI 42 mi, 13.6 days
Where these numbers come from
NOAA 1991–2020 climate normals from Port Huron, 1.5 miles from Port 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.