Tennessee is divided into six geographic regions. In the far eastern part of the state are the Unaka Mountains—which include the Great Smoky Mountains. The Unaka have more than a dozen peaks higher than 6,000 feet (1,830 meters); the tallest of them, Clingmans Dome, rises to 6,643 feet (2,025 meters). West of the Unakas is the Great Appalachian Valley of East Tennessee. The Great Valley is made up of long, narrow ridges with broad valleys between them. West of the Appalachian Valley is the Cumberland Plateau, which includes the Cumberland Mountains and the Sequatchie Valley. The Highland Rim, in Middle Tennessee, is the state's largest natural region. The eastern section is a gently rolling plain, while the western part sinks gently toward the Tennessee River. The Highland Rim surrounds the Central Basin, which is an oval depression with a gently rolling surface and rich soils. The westernmost region is the Gulf Coastal Plain. It includes most of West Tennessee and is a broad plain which slopes gradually westward until it ends abruptly at the bluffs overlooking the Mississippi Flood Plains. The state’s lowest point, 178 ft (54 m) above sea level, is on the banks of the Mississippi in the southwest.

The two longest rivers in the state are the Tennessee (652 miles/1,049 km long) and the Cumberland (687 miles/1,106 km long). The Tennessee flows southwestward through the Great Valley into northern Alabama, then curves back into the state and flows northward into Kentucky. Tributaries of the Tennessee include the Clinch, Duck, Elk, Hiwassee, and Sequatchie rivers. The Cumberland River rises in southeastern Kentucky, flows across central Tennessee, and then turns northward back into Kentucky; its principal tributaries are the Harpeth, Red, Obey, Caney Fork, and Stones rivers and Yellow Creek. In the western part of the state, the Forked Deer and Wolf rivers flow into the Mississippi. Dams have been built along the Tennessee and Cumberland rivers, which has created a chain of lakes, sometimes known as the Great Lakes of the South. In the northwest corner of the state is Reelfoot Lake, the only large natural lake in the state. It was formed by a series of earthquakes in 1811 and 1812.

Tennessee has a moderate climate, with cool winters and warm summers. The warmest parts of the state are the Gulf Coastal Plain, the Central Basin, and the Sequatchie Valley. Average temperatures in Memphis range from around 40°F (4°C) in January to 83°F (28°C) in July, while temperatures in Nashville range from 30°F (-1°C) in January to the high 80s°F (high 20s°C) in July. Temperatures are lower in the mountain areas in the east of the state. The record high temperature for the state is 113°F (45°C), set at Perryville on 9 August 1930; the record low, –32°F (–36°C), was registered at Mountain City on 30 December 1917. Average rainfall is around 51 inches (1,300mm) a year, and falls mostly in the winter and early spring. Snow is more common in East Tennessee than in the western parts of the state. Nashville gets about 10 in (25.4 cm) of snow a year, Memphis around 5 in (12.7 cm).