Frost line depth in Emmet County, IA
How deep the ground freezes in Emmet County, IA
51 in. Dig to 51 in, just below the frost. Nearest NOAA station: Estherville 4e, 4.3 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.