Ice dam risk in Arnold, MO
Ice dams in Arnold, MO: how often
2.1 dam days a winter
Low risk. On an ordinary house in Arnold, conditions for an ice dam come on about 2.1 days in a normal winter, mostly in January and February.
Arnold averages 9 inches of snow a year and about 9 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 Arnold
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 1.4 | Low |
| Typical, some insulation, not air-sealed | 2.1 | Low |
| Older or poorly insulated, warm attic | 2.9 | Low |
The attic matters less in Arnold than in colder towns: there are only 0.7 days a winter between a typical attic and a sealed one.
Preventing ice dams on a Arnold 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.
Arnold winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 2.1 | 3.4 | 0.9 |
| February | 2.7 | 2.8 | 0.6 |
| March | 1.1 | 0.7 | 0.1 |
| April | 0.2 | 0.0 | 0.0 |
| November | 0.6 | 0.3 | 0.0 |
| December | 2.5 | 1.7 | 0.4 |
Arnold next to nearby towns
Arnold ranks 67 of 80 Missouri cities here for ice-dam days, behind Maryville at 9.3 days.
- Columbia, IL 9 mi, 3.6 days
- Crestwood, MO 9 mi, 3.6 days
- Kirkwood, MO 11 mi, 4.2 days
- Webster Groves, MO 11 mi, 3.6 days
- Waterloo, IL 13 mi, 2.1 days
Where these numbers come from
NOAA 1991–2020 climate normals from Festus, 13.5 miles from Arnold. 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.