Frost line depth in Maricopa County, AZ

How deep the ground freezes in Maricopa County, AZ

no frost in a normal winter. Dig to 12 in, the 12 in code minimum. Nearest NOAA station: Litchfield Park, 13.2 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.