Ice dam risk in Rahway, NJ
Will your roof get ice dams in Rahway, NJ?
7.0 dam days a winter
Moderate risk. On an ordinary house in Rahway, conditions for an ice dam come on about 7.0 days in a normal winter, mostly in February and January.
Rahway averages 26 inches of snow a year and about 31 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 Rahway
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 5.4 | Moderate |
| Typical, some insulation, not air-sealed | 7.0 | Moderate |
| Older or poorly insulated, warm attic | 8.9 | Moderate |
The attic matters less in Rahway than in colder towns: there are only 1.6 days a winter between a typical attic and a sealed one.
Preventing ice dams on a Rahway roof
- 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.
Rahway winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 7.0 | 9.7 | 2.5 |
| February | 8.2 | 11.6 | 2.8 |
| March | 5.0 | 5.2 | 0.8 |
| April | 0.3 | 0.2 | 0.0 |
| November | 0.1 | 0.1 | 0.0 |
| December | 5.7 | 4.4 | 0.8 |
Rahway next to nearby towns
Rahway ranks 14 of 116 New Jersey cities here for ice-dam days, behind Hopatcong at 14.7 days.
- Linden, NJ 3 mi, 4.2 days
- Carteret, NJ 3 mi, 4.2 days
- Roselle, NJ 3 mi, 7.0 days
- Roselle Park, NJ 4 mi, 7.0 days
- Westfield, NJ 5 mi, 7.0 days
Where these numbers come from
NOAA 1991–2020 climate normals from Cranford, 4.7 miles from Rahway. 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.