Frost line depth in Mecosta County, MI
How deep the ground freezes in Mecosta County, MI
42 in. Dig to 42 in, just below the frost. Nearest NOAA station: Big Rapids Wtp, 9 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.