What is frost line depth for northern Missouri?

Answer 1

For northern Missouri, in Spickard, the coldest 8-inch soil temperature was 29° in 1977 and 1982 and the coldest 20-inch temperature was 35° in 1977, 1978 1994 and 1997. The coldest 40-inch temperature was 37° in 1986 and 1994. In mid-Missouri, the frost line at Columbia has also never reached the 20-inch depth. The coldest temperature at 20 inches was 35° in 1996, and the coldest 40-inch temperature was 42° in 1978. The coldest 8-inch temperature was 28° in 1982 and 1996. Soil temperature records in southern sections of the state indicate the frost line has never reached the 20-inch depth at Mount Vernon. The coldest temperature at the 8-inch depth was 28° in 1979 and the coldest 20-inch temperature was 36° in 1977 and 1979. The coldest 40-inch temperature was 40° in 1979.

Answer 2

The frost line in St. Louis is 30 inches.

Answer 3

The frost line less than 20 inches deep.