Frost line depth in Richmond County, NY
How deep the ground freezes in Richmond County, NY
17 in. Dig to 17 in, just below the frost. Nearest NOAA station: Newark Intl Ap, 8.5 mi.
Your building department sets the legal frost line depth (IRC Table R301.2(1)); footings must go below it (R403.1.4.1). Call them before you dig.