Furthermore, to delineate hot semi-arid climates from cold semi-arid climates, there are three widely used isotherms: either a mean annual temperature of , or a mean temperature of in the coldest month, so that a location with a "BS" type climate with the appropriate temperature above whichever isotherm is being used is classified as hot semi-arid ("BSh"), and a location with the appropriate temperature below the given isotherm is classified as cold semi-arid ("BSk").