Frost Depth

The maximum depth at which ground freezes in winter. Frost changes both what a locator can do and how long a locate lasts: frozen ground and snow cover interfere with radar, and marks on frozen or snow-covered surfaces do not hold.

Frost depth varies from nothing in warm climates to several feet across the northern United States and Canada. Its practical effect on locating is that surface marks become unreliable — paint will not bond to frozen or wet ground and snow buries flags — so winter work leans harder on recorded coordinates and offsets to permanent features. Frozen ground also alters the dielectric properties radar depends on, which can help or hurt depending on moisture content.