Ice dam risk in Moses Lake, WA
How often ice dams form in Moses Lake
6.7 dam days a winter
Moderate risk. On an ordinary house in Moses Lake, conditions for an ice dam come on about 6.7 days in a normal winter, mostly in January and December.
Moses Lake averages 14 inches of snow a year and about 25 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 Moses Lake
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 4.2 | Low |
| Typical, some insulation, not air-sealed | 6.7 | Moderate |
| Older or poorly insulated, warm attic | 9.8 | Moderate |
Sealing and insulating a typical attic takes out about 2.5 days a winter here. It drops the risk from moderate to low. An older house with a warm attic should expect closer to 9.8 days.
Preventing ice dams on a Moses Lake 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.
Which to spend on first: air sealing or heat cable.
Moses Lake winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 4.9 | 10.1 | 2.9 |
| February | 1.5 | 3.7 | 0.8 |
| March | 0.8 | 1.0 | 0.2 |
| November | 2.0 | 1.8 | 0.3 |
| December | 4.7 | 8.6 | 2.6 |
Moses Lake next to nearby towns
Moses Lake ranks 11 of 91 Washington cities here for ice-dam days, behind Spokane at 13.0 days.
- East Wenatchee, WA 51 mi, 7.6 days
- Wenatchee, WA 54 mi, 7.6 days
- West Richland, WA 56 mi, 0.3 days
- Richland, WA 58 mi, 0.3 days
- Pasco, WA 60 mi, 0.3 days
Where these numbers come from
NOAA 1991–2020 climate normals from Odessa, 30.7 miles from Moses Lake. 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.
- Snow-on-the-ground counts come from a second, nearby station, because the closest one does not record them.
- The weather station is 31 miles away, far enough that local snow can differ.