Ice dam risk in Godfrey, IL
Ice dams in Godfrey, IL: how often
4.8 dam days a winter
Low risk. On an ordinary house in Godfrey, conditions for an ice dam come on about 4.8 days in a normal winter, mostly in January and February.
Godfrey averages 13 inches of snow a year and about 18 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 Godfrey
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 2.9 | Low |
| Typical, some insulation, not air-sealed | 4.8 | Low |
| Older or poorly insulated, warm attic | 7.2 | Moderate |
The attic matters less in Godfrey than in colder towns: there are only 1.9 days a winter between a typical attic and a sealed one.
Preventing ice dams on a Godfrey 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.
Godfrey winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 4.3 | 8.1 | 2.5 |
| February | 3.7 | 4.4 | 1.1 |
| March | 1.6 | 1.3 | 0.2 |
| November | 0.7 | 0.7 | 0.1 |
| December | 2.2 | 3.3 | 0.8 |
Godfrey next to nearby towns
Godfrey ranks 203 of 225 Illinois cities here for ice-dam days, behind Arlington Heights at 21.5 days.
- Alton, IL 5 mi, 3.7 days
- Wood River, IL 10 mi, 3.7 days
- Florissant, MO 12 mi, 3.7 days
- Bellefontaine Neighbors, MO 14 mi, 3.7 days
- Hazelwood, MO 14 mi, 3.7 days
Where these numbers come from
NOAA 1991–2020 climate normals from Jerseyville 2 SW, 12.2 miles from Godfrey. 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.