Frost line depth in Pettis County, MO
How deep the ground freezes in Pettis County, MO
23 in. Dig to 23 in, just below the frost. Nearest NOAA station: Sedalia Wtp, 4.9 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.