Four hardiness zones exist. USDA zone 11b with average extreme annual lows between is found from Key West to Marathon and 11a, , in the remaining keys, Miami Beach, and some of downtown Miami. Zone 10b is found in coastal South Florida and much of the Everglades where annual extreme low temperatures range from . Zone 10a, is found in the rest of South Florida, and in certain coastal regions as far north as St.Petersburg on the west coast and roughly Vero Beach on the east coast mainland. Next is zone 9b, , across interior central Florida, changing over to 9a, , just north of Orlando. The coolest, zone 8b, is located in northwestern Florida from roughly Gainesville and northwest including Tallahassee. Low temperatures range from . Formally, there exist very small isolated areas near the Georgia border classified as zone 8a with extreme low averages of around 14.9°F.