Ice dam risk in Hempstead, NY

Ice dams in Hempstead, NY: how often

3.9 dam days a winter

Low risk. On an ordinary house in Hempstead, conditions for an ice dam come on about 3.9 days in a normal winter, mostly in February and January.

Hempstead averages 19 inches of snow a year and about 20 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 Hempstead

Attic	Dam days	Risk
Air-sealed and well insulated	2.9	Low
Typical, some insulation, not air-sealed	3.9	Low
Older or poorly insulated, warm attic	5.0	Low

The attic matters less in Hempstead than in colder towns: there are only 1.0 day a winter between a typical attic and a sealed one.

What to do about ice dams in Hempstead

Check the gutters before the first snow and clear them, so meltwater has somewhere to go. If you see icicles thicker than a finger along the eave after a storm, that is the early sign to look at the attic.

Snowy places are not always the worst: why snowfall misleads.

Hempstead winter, month by month

Month	Snow (in)	Days on ground	Dam days
January	2.9	6.2	1.4
February	6.2	7.3	1.6
March	3.1	3.3	0.4
April	0.4	0.2	0.0
November	0.2	0.2	0.0
December	5.7	2.8	0.5

Hempstead next to nearby towns

Hempstead ranks 77 of 90 New York cities here for ice-dam days, behind Utica at 46.1 days.

Garden City, NY 2 mi, 3.9 days
Rockville Centre, NY 3 mi, 3.9 days
Mineola, NY 3 mi, 3.9 days
New Hyde Park, NY 4 mi, 3.9 days
Freeport, NY 4 mi, 3.9 days

Where these numbers come from

NOAA 1991–2020 climate normals from Mineola, 2.0 miles from Hempstead. 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.