Ice dam risk in Effingham, IL
Ice dams in Effingham, IL: how often
5.2 dam days a winter
Moderate risk. On an ordinary house in Effingham, conditions for an ice dam come on about 5.2 days in a normal winter, mostly in January and February.
Effingham averages 15 inches of snow a year and about 20 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 Effingham
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 3.2 | Low |
| Typical, some insulation, not air-sealed | 5.2 | Moderate |
| Older or poorly insulated, warm attic | 7.7 | Moderate |
Sealing and insulating a typical attic takes out about 2.0 days a winter here. It drops the risk from moderate to low.
What to do about ice dams in Effingham
- 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.
Effingham winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 5.3 | 7.6 | 2.3 |
| February | 4.6 | 6.1 | 1.6 |
| March | 1.5 | 1.7 | 0.3 |
| April | 0.2 | 0.1 | 0.0 |
| November | 0.6 | 0.6 | 0.1 |
| December | 2.4 | 4.2 | 1.0 |
Effingham next to nearby towns
Effingham ranks 202 of 225 Illinois cities here for ice-dam days, behind Arlington Heights at 21.5 days.
- Mattoon, IL 27 mi, 5.4 days
- Charleston, IL 32 mi, 6.8 days
- Taylorville, IL 51 mi, 6.3 days
- Centralia, IL 52 mi, 4.1 days
- Decatur, IL 55 mi, 6.9 days
Where these numbers come from
NOAA 1991–2020 climate normals from Effingham 3SW, 3.9 miles from Effingham. 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.