Ice dam risk in Fort Collins, CO
Will your roof get ice dams in Fort Collins, CO?
10.5 dam days a winter
Moderate risk. On an ordinary house in Fort Collins, conditions for an ice dam come on about 10.5 days in a normal winter, mostly in January and December.
Fort Collins averages 51 inches of snow a year and about 44 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 Fort Collins
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 8.6 | Moderate |
| Typical, some insulation, not air-sealed | 10.5 | Moderate |
| Older or poorly insulated, warm attic | 12.9 | Moderate |
The attic matters less in Fort Collins than in colder towns: there are only 1.9 days a winter between a typical attic and a sealed one.
What to do about ice dams in Fort Collins
- Rake the bottom three or four feet of roof after any storm that leaves more than about six inches, from the ground with a roof rake.
More on when a roof rake is worth it.
Fort Collins winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 6.7 | 12.3 | 3.3 |
| February | 7.6 | 8.3 | 2.1 |
| March | 9.4 | 3.9 | 0.7 |
| April | 6.2 | 1.5 | 0.1 |
| May | 1.6 | 0.3 | 0.0 |
| September | 0.7 | 0.1 | 0.0 |
| October | 4.1 | 1.3 | 0.1 |
| November | 7.6 | 4.5 | 1.0 |
| December | 7.5 | 11.4 | 3.2 |
Fort Collins next to nearby towns
Fort Collins ranks 26 of 53 Colorado cities here for ice-dam days, behind Steamboat Springs at 51.0 days.
- Timnath, CO 5 mi, 11.6 days
- Loveland, CO 9 mi, 12.7 days
- Windsor, CO 9 mi, 11.6 days
- Wellington, CO 11 mi, 11.6 days
- Severance, CO 11 mi, 11.6 days
Where these numbers come from
NOAA 1991–2020 climate normals from Ft Collins, 2.2 miles from Fort Collins. 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.