south, southern

As a compass direction, south and southern are not capitalized:

            He lived south of Washington.

            He lived in the southern part of the state.

Capitalize each term when it is used as a proper name or as part of a proper name, and if the region is widely known:

            The Civil War pitted the South against the North.

            He moved to South Florida.

            Southern California has many lovely beaches. 

While the region (South) and residents (Southerner) are capped, NG style is lowercase for adjectives describing the region's features, such as chef, cuisine, and accent. 

See also north, northern, pole, polar.