Frost line depth in Mono County, CA

How deep the ground freezes in Mono County, CA

19 in. Dig to 20 in, just below the frost. Nearest NOAA station: Lee Vining, 13.6 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.