Ice dam risk in Cape Girardeau, MO
How often ice dams form in Cape Girardeau
2.1 dam days a winter
Low risk. On an ordinary house in Cape Girardeau, conditions for an ice dam come on about 2.1 days in a normal winter, mostly in January and February.
Cape Girardeau averages 8 inches of snow a year and about 10 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 Cape Girardeau
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 1.5 | Low |
| Typical, some insulation, not air-sealed | 2.1 | Low |
| Older or poorly insulated, warm attic | 2.9 | Low |
The attic matters less in Cape Girardeau than in colder towns: there are only 0.6 days a winter between a typical attic and a sealed one.
What to do about ice dams in Cape Girardeau
- 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.
Cape Girardeau winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 2.2 | 4.2 | 1.0 |
| February | 1.2 | 2.8 | 0.6 |
| March | 1.5 | 0.5 | 0.0 |
| October | 0.1 | 0.0 | 0.0 |
| November | 0.1 | 0.0 | 0.0 |
| December | 2.4 | 2.6 | 0.5 |
Cape Girardeau next to nearby towns
Cape Girardeau ranks 66 of 80 Missouri cities here for ice-dam days, behind Maryville at 9.3 days.
- Jackson, MO 7 mi, 2.1 days
- Sikeston, MO 29 mi, 0.3 days
- Carbondale, IL 34 mi, 2.3 days
- Herrin, IL 44 mi, 3.1 days
- Marion, IL 45 mi, 3.1 days
Where these numbers come from
NOAA 1991–2020 climate normals from Jackson, 7.7 miles from Cape Girardeau. 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.
- Snow-on-the-ground counts come from a second, nearby station, because the closest one does not record them.