Ice dam risk in Eureka, MO
How often ice dams form in Eureka
3.6 dam days a winter
Low risk. On an ordinary house in Eureka, conditions for an ice dam come on about 3.6 days in a normal winter, mostly in January and February.
Eureka 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 Eureka
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 2.3 | Low |
| Typical, some insulation, not air-sealed | 3.6 | Low |
| Older or poorly insulated, warm attic | 5.1 | Moderate |
The attic matters less in Eureka than in colder towns: there are only 1.3 days a winter between a typical attic and a sealed one.
Preventing ice dams on a Eureka 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.
Eureka winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 4.1 | 5.4 | 1.5 |
| February | 3.7 | 4.1 | 1.0 |
| March | 1.7 | 1.2 | 0.2 |
| April | 0.2 | 0.0 | 0.0 |
| November | 0.8 | 0.7 | 0.1 |
| December | 3.0 | 3.5 | 0.8 |
Eureka next to nearby towns
Eureka ranks 53 of 80 Missouri cities here for ice-dam days, behind Maryville at 9.3 days.
- Wildwood, MO 6 mi, 3.6 days
- Ellisville, MO 7 mi, 3.6 days
- Ballwin, MO 8 mi, 3.6 days
- Manchester, MO 10 mi, 3.6 days
- Chesterfield, MO 12 mi, 3.6 days
Where these numbers come from
NOAA 1991–2020 climate normals from Weldon Spring NWS, 14.0 miles from Eureka. 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.