In general, the frost line in Montana varies depending on the location. Eastern Montana, which has a more continental climate, tends to have a deeper frost line than western Montana, which has a more maritime climate. On average, the frost line depth is around 24 to 36 inches in eastern Montana, while in western Montana, it can be as shallow as 12 inches.
It is important to consider the frost line when determining the depth of footings for structures, such as buildings, decks, and fences, to ensure they are properly anchored and protected against frost heave. Local building codes and regulations often provide guidelines for determining the appropriate frost depth based on the specific location and soil conditions.
