Chiba Prefecture Chōnan has a humid subtropical climate (Köppen Cfa) characterized by warm summers and cool winters with light to no snowfall.

After the establishment of the Tokugawa shogunate Chōnan became a major distribution center of goods, most notably salt, passing through the Bōsō Peninsula.

Chōnan has a mayor-council form of government with a directly elected mayor and a unicameral town council of 13 members.

In terms of national politics, the town is part of Chiba 11th district of the lower house of the Diet of Japan.

The principal agricultural output of Chōnan is rice, and shiitake mushrooms and lotus root are cultivated in the town.