Ice dam risk in Montrose, CO
Ice dams in Montrose, CO: how often
10.1 dam days a winter
Moderate risk. On an ordinary house in Montrose, conditions for an ice dam come on about 10.1 days in a normal winter, mostly in January and December.
Montrose averages 22 inches of snow a year and about 36 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 Montrose
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 7.5 | Moderate |
| Typical, some insulation, not air-sealed | 10.1 | Moderate |
| Older or poorly insulated, warm attic | 13.3 | Moderate |
Sealing and insulating a typical attic takes out about 2.6 days a winter here. It does not move the risk band, but it shortens every dam. An older house with a warm attic should expect closer to 13.3 days.
Preventing ice dams on a Montrose roof
- Air-seal the attic floor: the gaps around the hatch, light fixtures, plumbing stacks and the top plates of interior walls. This is the fix that removes the cause, and it usually costs less than a season of contractor ice removal.
- 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.
Which to spend on first: air sealing or heat cable.
Montrose winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 4.7 | 15.9 | 4.7 |
| February | 3.9 | 5.6 | 1.4 |
| March | 2.2 | 1.8 | 0.3 |
| April | 0.6 | 0.4 | 0.0 |
| October | 0.5 | 0.5 | 0.0 |
| November | 2.7 | 1.7 | 0.4 |
| December | 6.9 | 10.5 | 3.2 |
Montrose next to nearby towns
Montrose ranks 29 of 53 Colorado cities here for ice-dam days, behind Steamboat Springs at 51.0 days.
- Grand Junction, CO 57 mi, 6.9 days
- Fruita, CO 67 mi, 6.2 days
- Rifle, CO 74 mi, 16.6 days
- Glenwood Springs, CO 79 mi, 15.9 days
- Durango, CO 83 mi, 30.8 days
Where these numbers come from
NOAA 1991–2020 climate normals from Montrose #2, 1.6 miles from Montrose. 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.
- The nearest weather station sits at a noticeably different elevation from Montrose, so the snow figures may run high or low for the town itself.