Ice dam risk in Grand Island, NE
Will your roof get ice dams in Grand Island, NE?
11.6 dam days a winter
Moderate risk. On an ordinary house in Grand Island, conditions for an ice dam come on about 11.6 days in a normal winter, mostly in January and February.
Grand Island averages 28 inches of snow a year and about 38 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 Grand Island
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 6.7 | Moderate |
| Typical, some insulation, not air-sealed | 11.6 | Moderate |
| Older or poorly insulated, warm attic | 17.7 | High |
Sealing and insulating a typical attic takes out about 4.9 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 17.7 days.
What to do about ice dams in Grand Island
- 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.
Grand Island winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 6.8 | 12.5 | 4.3 |
| February | 7.3 | 11.0 | 3.5 |
| March | 3.8 | 3.1 | 0.6 |
| April | 1.6 | 0.8 | 0.1 |
| September | 0.1 | 0.0 | 0.0 |
| October | 1.1 | 0.5 | 0.0 |
| November | 2.3 | 2.2 | 0.5 |
| December | 4.7 | 8.3 | 2.7 |
Grand Island next to nearby towns
Grand Island ranks 10 of 16 Nebraska cities here for ice-dam days, behind South Sioux City at 19.2 days.
- Hastings, NE 23 mi, 11.3 days
- Kearney, NE 41 mi, 10.1 days
- Columbus, NE 63 mi, 12.5 days
- Lexington, NE 73 mi, 13.8 days
- Lincoln, NE 88 mi, 11.4 days
Where these numbers come from
NOAA 1991–2020 climate normals from Grand Is Cntrl NE Regional Airport, 3.6 miles from Grand Island. 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.