South Carolina has a humid subtropical climate with hot summers and mild winters, receiving abundant rainfall throughout the year. The state's major surface flows include the Savannah River, Santee River, and Cooper River, which all flow into the Atlantic Ocean. There are several major reservoirs and dams in the state, including the Lake Marion, Lake Murray, and Lake Moultrie. The state's hydrology is heavily influenced by the Atlantic Ocean and Gulf of Mexico, as well as by the Appalachian Mountains in the western part of the state. Snowpack is generally limited in South Carolina, and the state's watershed is primarily influenced by rainfall and runoff. Major tributaries of the state's major rivers include the Broad River, Edisto River, and Pee Dee River.