Ice dam risk in St. Peters, MO
Ice dams in St. Peters, MO: how often
4.2 dam days a winter
Low risk. On an ordinary house in St. Peters, conditions for an ice dam come on about 4.2 days in a normal winter, mostly in January and February.
St. Peters averages 15 inches of snow a year and about 17 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 St. Peters
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 2.7 | Low |
| Typical, some insulation, not air-sealed | 4.2 | Low |
| Older or poorly insulated, warm attic | 6.0 | Moderate |
The attic matters less in St. Peters than in colder towns: there are only 1.5 days a winter between a typical attic and a sealed one.
What to do about ice dams in St. Peters
- 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.
St. Peters winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 4.7 | 6.1 | 1.8 |
| February | 5.0 | 5.2 | 1.3 |
| March | 1.5 | 1.4 | 0.2 |
| April | 0.1 | 0.0 | 0.0 |
| November | 0.8 | 0.6 | 0.1 |
| December | 2.7 | 3.8 | 0.8 |
St. Peters next to nearby towns
St. Peters ranks 23 of 80 Missouri cities here for ice-dam days, behind Maryville at 9.3 days.
- St. Charles, MO 5 mi, 4.1 days
- O'Fallon, MO 6 mi, 3.6 days
- Dardenne Prairie, MO 7 mi, 3.6 days
- Maryland Heights, MO 8 mi, 4.2 days
- Chesterfield, MO 9 mi, 3.6 days
Where these numbers come from
NOAA 1991–2020 climate normals from St Peters 2 SE, 1.2 miles from St. Peters. 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.