The Savannah River is a major river in the southeastern United States, forming most of the border between the states of South Carolina and Georgia. Two tributaries of the Savannah, the Tugaloo River and the Chattooga River, form the northernmost part of the border. The Savannah River drainage basin extends into the southeastern side of the Appalachian Mountains just inside North Carolina, bounded by the Eastern Continental Divide. The river is around 350 miles (560 km) long. It is formed by the confluence of the Tugaloo River and the Seneca River. Today this confluence is submerged beneath Lake Hartwell. At the northwest branch of the river is located the Tallulah Gorge.
Two major cities are located along the Savannah River: Savannah, Georgia, and Augusta, Georgia. They were nuclei of early English settlements during the Colonial period of American history. Through the building of several locks and dams, and upstream reservoirs like Lake Hartwell, also, the Savannah River was once navigable by freight barges between Augusta, Georgia, (on the Fall Line) and the Atlantic Ocean; maintenance of this channel for commercial shipping ended in 1979 and the one lock below Augusta has been deactivated.
The Savannah River is tidal at Savannah, Georgia and downstream. From Savannah downstream, the river broadens into an estuary before flowing into the Atlantic Ocean. The area where the river's estuary meets the ocean is known as "Tybee Roads". The Intracoastal Waterway flows through a section of the Savannah River near the city of Savannah.
Savannah's climate is classified as humid subtropical (Köppen climate classification Cfa) and is characterized by hot, humid summers and cool winters. Due to its proximity to the Atlantic coast, Savannah experiences milder winters and cooler summers than the Georgia interior. Despite this, temperatures as high as 105°F and as low as 3°F have been recorded. Summers tend to be humid with many thunderstorms. Nearly half of Savannah's precipitation falls during the months of June through September, characteristic of monsoon-type climates. As the city is south of the snow line, it rarely receives snow in winter. Occasional Arctic cold fronts in winter can push nighttime temperatures into the 20s, but usually not much further than that.
Savannah is at risk for hurricanes, particularly of the Cape Verde type. Because of its location in the Georgia Bight (the arc of the Atlantic coastline in Georgia and northern Florida) as well as the tendency for hurricanes to re-curve up the coast, Savannah has a lower risk of hurricanes than some other coastal cities such as Charleston, South Carolina. Savannah was seldom affected by hurricanes during the twentieth century, with one exception being Hurricane David in 1979. However, the historical record shows that the city was frequently affected during the second half of the nineteenth century. The most prominent of these storms was the 1893 Sea Islands hurricane, which killed at least 2,000 people. (This estimate may be low, as deaths among the many impoverished rural African-Americans living on Georgia's barrier ...