Ice dam risk in Columbia, IL
Ice dams in Columbia, IL: how often
3.6 dam days a winter
Low risk. On an ordinary house in Columbia, conditions for an ice dam come on about 3.6 days in a normal winter, mostly in January and December.
Columbia averages 14 inches of snow a year and about 15 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 Columbia
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 2.4 | Low |
| Typical, some insulation, not air-sealed | 3.6 | Low |
| Older or poorly insulated, warm attic | 5.0 | Low |
The attic matters less in Columbia than in colder towns: there are only 1.2 days a winter between a typical attic and a sealed one.
Preventing ice dams on a Columbia 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.
Columbia winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 4.9 | 7.2 | 1.9 |
| February | 3.7 | 3.5 | 0.7 |
| March | 1.2 | 0.6 | 0.1 |
| April | 0.3 | 0.1 | 0.0 |
| November | 0.8 | 0.5 | 0.0 |
| December | 2.9 | 3.5 | 0.8 |
Columbia next to nearby towns
Columbia ranks 213 of 225 Illinois cities here for ice-dam days, behind Arlington Heights at 21.5 days.
- Cahokia Heights, IL 9 mi, 3.6 days
- Arnold, MO 9 mi, 2.1 days
- Waterloo, IL 9 mi, 2.1 days
- Crestwood, MO 11 mi, 3.6 days
- Webster Groves, MO 12 mi, 3.6 days
Where these numbers come from
NOAA 1991–2020 climate normals from Cahokia, 7.6 miles from Columbia. 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.