Ice dam risk in Chesterfield, MO
Ice dams in Chesterfield, MO: how often
3.6 dam days a winter
Low risk. On an ordinary house in Chesterfield, conditions for an ice dam come on about 3.6 days in a normal winter, mostly in January and February.
Chesterfield averages 8 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 Chesterfield
| 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 | 5.1 | Moderate |
The attic matters less in Chesterfield than in colder towns: there are only 1.2 days a winter between a typical attic and a sealed one.
What to do about ice dams in Chesterfield
- 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.
Chesterfield winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 4.2 | 5.4 | 1.6 |
| February | 1.1 | 4.1 | 1.0 |
| March | 0.3 | 1.2 | 0.2 |
| November | 0.4 | 0.7 | 0.1 |
| December | 2.1 | 3.5 | 0.8 |
Chesterfield next to nearby towns
Chesterfield ranks 45 of 80 Missouri cities here for ice-dam days, behind Maryville at 9.3 days.
- Ballwin, MO 5 mi, 3.6 days
- Ellisville, MO 5 mi, 3.6 days
- Town and Country, MO 6 mi, 4.2 days
- Manchester, MO 6 mi, 3.6 days
- Maryland Heights, MO 7 mi, 4.2 days
Where these numbers come from
NOAA 1991–2020 climate normals from St Charles 7 SSW, 3.4 miles from Chesterfield. 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.
- Snow-on-the-ground counts come from a second, nearby station, because the closest one does not record them.