Ice dam risk in Lincoln, IL
How often ice dams form in Lincoln
7.4 dam days a winter
Moderate risk. On an ordinary house in Lincoln, conditions for an ice dam come on about 7.4 days in a normal winter, mostly in January and February.
Lincoln averages 19 inches of snow a year and about 25 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 Lincoln
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 4.2 | Low |
| Typical, some insulation, not air-sealed | 7.4 | Moderate |
| Older or poorly insulated, warm attic | 11.4 | Moderate |
Sealing and insulating a typical attic takes out about 3.2 days a winter here. It drops the risk from moderate to low. An older house with a warm attic should expect closer to 11.4 days.
What to do about ice dams in Lincoln
- 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.
Which to spend on first: air sealing or heat cable.
Lincoln winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 5.7 | 11.0 | 3.6 |
| February | 6.2 | 6.5 | 1.9 |
| March | 1.8 | 1.5 | 0.3 |
| October | 0.1 | 0.0 | 0.0 |
| November | 0.6 | 0.6 | 0.1 |
| December | 4.9 | 5.7 | 1.6 |
Lincoln next to nearby towns
Lincoln ranks 193 of 225 Illinois cities here for ice-dam days, behind Arlington Heights at 21.5 days.
- Springfield, IL 29 mi, 7.1 days
- Decatur, IL 31 mi, 6.9 days
- Bloomington, IL 31 mi, 9.8 days
- Pekin, IL 32 mi, 10.3 days
- Normal, IL 32 mi, 9.8 days
Where these numbers come from
NOAA 1991–2020 climate normals from Lincoln, 1.7 miles from Lincoln. 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.