Ice dam risk in Vernal, UT
Ice dams in Vernal, UT: how often
20.9 dam days a winter
High risk. On an ordinary house in Vernal, conditions for an ice dam come on about 20.9 days in a normal winter, mostly in January and December.
Vernal averages 20 inches of snow a year and about 61 days with snow on the ground. Snow that lies that long is what turns a little attic heat into a ridge of ice at the eave. 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 Vernal
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 11.0 | Moderate |
| Typical, some insulation, not air-sealed | 20.9 | High |
| Older or poorly insulated, warm attic | 33.4 | High |
Sealing and insulating a typical attic takes out about 10.0 days a winter here. It drops the risk from high to moderate. An older house with a warm attic should expect closer to 33.4 days.
What to do about ice dams in Vernal
- 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.
- At the next reroof, ask for ice-and-water membrane under the shingles from the eave to at least 24 inches inside the wall line. It does not stop a dam; it stops the leak when one forms.
Which to spend on first: air sealing or heat cable.
Vernal winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 5.8 | 22.9 | 8.9 |
| February | 3.9 | 15.8 | 5.0 |
| March | 1.6 | 3.9 | 0.8 |
| April | 0.6 | 0.3 | 0.0 |
| October | 0.5 | 0.5 | 0.1 |
| November | 1.6 | 1.5 | 0.4 |
| December | 6.4 | 15.6 | 5.8 |
Vernal next to nearby towns
Vernal ranks 9 of 67 Utah cities here for ice-dam days, behind Ogden at 37.2 days.
- Green River, WY 73 mi, 23.1 days
- Rock Springs, WY 81 mi, 13.9 days
- Evanston, WY 93 mi, 32.8 days
- Heber, UT 97 mi, 21.5 days
- Fruita, CO 99 mi, 6.2 days
Where these numbers come from
NOAA 1991–2020 climate normals from Vernal, 0.8 miles from Vernal. 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 Vernal, so the snow figures may run high or low for the town itself.