Tennessee has a temperate climate, with warm summers and mild winters. However, the state's varied topography leads to a wide range of climatic conditions.

The warmest parts of the state, with the longest growing season, are the Gulf Coastal Plain, the Central Basin, and the Sequatchie Valley. Memphis has an annual mean temperature of 62°F (17°C), 40°F (4°C) in January, and 83°F (28°C) in July. In the Nashville area, the growing season lasts about 225 days and the annual mean temperature is  59°F (15°C), ranging from 36°F (2°C).

Severe storms occur occasionally. The greatest rainfall occurs in the winter and early spring, especially March. The early fall months, particularly September and October, are the driest. Snowfall varies and is more prevalent in East Tennessee than in the western section. Nashville receives about 10 inches of snowfall (25.4 cm) a year, Memphis only 5 inches (12.7 cm).

The Highland Rim, also in Middle Tennessee, is the state's largest natural region, consisting of more than 12,500 sq mi (32,400 sq km) and encircling the Central Basin. The eastern section is a gently rolling plain some 1,000 ft (300 m) lower than the Cumberland Plateau while the western part has an even lower elevation and sinks gently toward the Tennessee River.

The Central Basin has rich fertile soil and has attracted people from the days of the European settlement and is more densely populated than any other state.

The Gulf Coastal Plain is the westernmost region of the state and covers an area of 9,000 sq mi (23,000 sq km). It is a broad plain, sloping gradually westward until it ends abruptly at the bluffs overlooking the Mississippi Flood Plains. In the northwest corner is Reelfoot Lake, the only natural lake of significance in the state, formed by a series of earthquakes in 1811 and 1812. The state's lowest point, 178 ft (54 m) is on the banks of the Mississippi in the southwest.

Most of the state is drained by the Mississippi River system. Waters from the two longest rivers—the Tennessee and the Cumberland flow into the Ohio River in Kentucky and join the Mississippi at Cairo, Illinois. The Cumberland River rises in southeastern Kentucky, flows across central Tennessee, and then turns northward back into Kentucky. The main tributaries of Cumberland 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 are among those flowing into the Mississippi, which forms the western border with Missouri and Arkansas.