Ice dam risk in Louisville/Jefferson County, KY
How often ice dams form in Louisville/Jefferson County
2.3 dam days a winter
Low risk. On an ordinary house in Louisville/Jefferson County, conditions for an ice dam come on about 2.3 days in a normal winter, mostly in January and February.
Louisville/Jefferson County averages 15 inches of snow a year and about 11 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 Louisville/Jefferson County
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 1.6 | Low |
| Typical, some insulation, not air-sealed | 2.3 | Low |
| Older or poorly insulated, warm attic | 3.2 | Low |
The attic matters less in Louisville/Jefferson County than in colder towns: there are only 0.7 days a winter between a typical attic and a sealed one.
What to do about ice dams in Louisville/Jefferson County
- 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.
Louisville/Jefferson County winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 4.6 | 4.3 | 1.0 |
| February | 4.7 | 3.5 | 0.7 |
| March | 2.6 | 0.9 | 0.1 |
| April | 0.1 | 0.0 | 0.0 |
| November | 0.4 | 0.1 | 0.0 |
| December | 2.7 | 2.5 | 0.5 |
Louisville/Jefferson County next to nearby towns
Louisville/Jefferson County ranks 16 of 42 Kentucky cities here for ice-dam days, behind Fort Thomas at 6.8 days.
- Jeffersontown, KY 5 mi, 2.3 days
- St. Matthews, KY 6 mi, 2.0 days
- Lyndon, KY 7 mi, 2.0 days
- Shively, KY 9 mi, 2.0 days
- Mount Washington, KY 10 mi, 2.3 days
Where these numbers come from
NOAA 1991–2020 climate normals from Louisville Wfo, 3.5 miles from Louisville/Jefferson County. 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.