Ice dam risk in University City, MO

Ice dams in University City, MO: how often

3.7 dam days a winter

Low risk. On an ordinary house in University City, conditions for an ice dam come on about 3.7 days in a normal winter, mostly in January and February.

University City averages 17 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 University City

Attic	Dam days	Risk
Air-sealed and well insulated	2.4	Low
Typical, some insulation, not air-sealed	3.7	Low
Older or poorly insulated, warm attic	5.4	Moderate

The attic matters less in University City than in colder towns: there are only 1.3 days a winter between a typical attic and a sealed one.

Preventing ice dams on a University City 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.

University City winter, month by month

Month	Snow (in)	Days on ground	Dam days
January	5.7	7.2	1.9
February	4.3	4.3	0.9
March	2.3	1.4	0.1
April	0.2	0.0	0.0
November	0.9	0.7	0.1
December	3.2	3.8	0.8

University City next to nearby towns

University City ranks 33 of 80 Missouri cities here for ice-dam days, behind Maryville at 9.3 days.

Clayton, MO 1 mi, 3.7 days
Overland, MO 3 mi, 3.7 days
St. Louis, MO 5 mi, 3.6 days
St. Ann, MO 5 mi, 3.7 days
Jennings, MO 5 mi, 3.7 days

Where these numbers come from

NOAA 1991–2020 climate normals from St Louis Lambert International Airport, 6.4 miles from University City. 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.