Ice dam risk in Kewanee, IL
Ice dams in Kewanee, IL: how often
14.1 dam days a winter
Moderate risk. On an ordinary house in Kewanee, conditions for an ice dam come on about 14.1 days in a normal winter, mostly in January and February.
Kewanee averages 31 inches of snow a year and about 42 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 Kewanee
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 6.6 | Moderate |
| Typical, some insulation, not air-sealed | 14.1 | Moderate |
| Older or poorly insulated, warm attic | 23.4 | High |
Sealing and insulating a typical attic takes out about 7.5 days a winter here. It does not move the risk band, but it shortens every dam. An older house with a warm attic should expect closer to 23.4 days.
Preventing ice dams on a Kewanee roof
- 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.
Which to spend on first: air sealing or heat cable.
Kewanee winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 8.7 | 16.0 | 6.1 |
| February | 8.5 | 11.7 | 4.0 |
| March | 3.2 | 3.2 | 0.7 |
| April | 1.2 | 0.4 | 0.0 |
| October | 0.3 | 0.1 | 0.0 |
| November | 1.4 | 1.2 | 0.2 |
| December | 7.5 | 9.3 | 3.0 |
Kewanee next to nearby towns
Kewanee ranks 82 of 225 Illinois cities here for ice-dam days, behind Arlington Heights at 21.5 days.
- Galesburg, IL 31 mi, 13.8 days
- East Moline, IL 31 mi, 15.9 days
- Moline, IL 34 mi, 15.9 days
- Bettendorf, IA 36 mi, 15.9 days
- Peoria, IL 37 mi, 10.3 days
Where these numbers come from
NOAA 1991–2020 climate normals from Kewanee 1 E, 1.4 miles from Kewanee. 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.