The northern Uinta Basin area covers about 5,200 square miles (13,470 square kilometers) in northeastern Utah and northwestern Colorado. Much of the lowlands are arid to semiarid, but the highest parts of the Uinta Mountains have a humid climate. During 1941-70, the average annual precipitation ranged from less than 8 inches (203 millimeters) in the lowest part of the area at the Green River to more than 38 inches (965 millimeters) in the high west-central Uinta Mountains.