Frost line depth in Santa Fe County, NM
How deep the ground freezes in Santa Fe County, NM
18 in. Dig to 19 in, just below the frost. Nearest NOAA station: Santa Fe Seton, 6.2 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.