Frost line depth in Lewis and Clark County, MT

How deep the ground freezes in Lewis and Clark County, MT

41 in. Dig to 42 in, just below the frost. Nearest NOAA station: Rogers Pass 9 Nne, 6.4 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.

Code depth · Snow