Frost line depth in Northwest Hills Planning Region, CT
How deep the ground freezes in Northwest Hills Planning Region, CT
38 in. Dig to 39 in, just below the frost. Nearest NOAA station: Norfolk 2 Sw, 8.1 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.