Ice dam risk in Columbia, MO
How often ice dams form in Columbia
4.6 dam days a winter
Low risk. On an ordinary house in Columbia, conditions for an ice dam come on about 4.6 days in a normal winter, mostly in January and February.
Columbia averages 17 inches of snow a year and about 20 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 Columbia
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 2.9 | Low |
| Typical, some insulation, not air-sealed | 4.6 | Low |
| Older or poorly insulated, warm attic | 6.7 | Moderate |
The attic matters less in Columbia than in colder towns: there are only 1.7 days a winter between a typical attic and a sealed one.
Preventing ice dams on a Columbia 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.
Columbia winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 5.9 | 7.5 | 2.0 |
| February | 4.8 | 5.4 | 1.2 |
| March | 2.0 | 1.7 | 0.2 |
| April | 0.3 | 0.1 | 0.0 |
| October | 0.1 | 0.0 | 0.0 |
| November | 0.8 | 0.5 | 0.0 |
| December | 3.5 | 4.9 | 1.1 |
Columbia next to nearby towns
Columbia ranks 19 of 80 Missouri cities here for ice-dam days, behind Maryville at 9.3 days.
- Fulton, MO 21 mi, 6.3 days
- Jefferson City, MO 27 mi, 4.1 days
- Mexico, MO 29 mi, 6.3 days
- Moberly, MO 33 mi, 2.9 days
- Marshall, MO 48 mi, 2.0 days
Where these numbers come from
NOAA 1991–2020 climate normals from Columbia U Of M, 0.5 miles from Columbia. 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.