Ice dam risk in Union, MO
Will your roof get ice dams in Union, MO?
3.1 dam days a winter
Low risk. On an ordinary house in Union, conditions for an ice dam come on about 3.1 days in a normal winter, mostly in January and December.
Union averages 14 inches of snow a year and about 14 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 Union
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 2.3 | Low |
| Typical, some insulation, not air-sealed | 3.1 | Low |
| Older or poorly insulated, warm attic | 4.2 | Low |
The attic matters less in Union than in colder towns: there are only 0.8 days a winter between a typical attic and a sealed one.
Preventing ice dams on a Union 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.
Union winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 4.7 | 6.2 | 1.6 |
| February | 4.1 | 2.8 | 0.6 |
| March | 1.8 | 0.9 | 0.1 |
| April | 0.2 | 0.1 | 0.0 |
| November | 0.7 | 0.5 | 0.1 |
| December | 2.9 | 3.9 | 0.8 |
Union next to nearby towns
Union ranks 57 of 80 Missouri cities here for ice-dam days, behind Maryville at 9.3 days.
- Washington, MO 8 mi, 3.7 days
- Eureka, MO 19 mi, 3.6 days
- Wildwood, MO 20 mi, 3.6 days
- Ellisville, MO 24 mi, 3.6 days
- Dardenne Prairie, MO 26 mi, 3.6 days
Where these numbers come from
NOAA 1991–2020 climate normals from Union, 0.6 miles from Union. 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.