The first European settlers in this area were French colonists, whose culture still influences the small city and who imported enslaved people from Africa.

A Louisiana Creole population developed, featuring people of color as well as white colonists of largely French descent.

While more Protestant Americans migrated into this area after Indian Removal in the 1830s, there are still many Catholic families, some dating to both African and French ancestors of the colonial era.

It is situated on the west side of the Bay of St. Louis which empties into the Mississippi Sound, adjacent to Pass Christian to the east.

On August 29, 2005, at 10:00 a.m. CDT, Hurricane Katrina made its final landfall just west of Bay St. Louis, at the mouth of the Pearl River, causing a 28-foot (8.5 m) storm surge.

USGS topographic maps show a common 25-foot (7.6 m) elevation contour line running throughout a ridge along the former routing of Highway 90 (Old Spanish Trail) on the western edge of the city.

[citation needed] The climate in this area is characterized by hot, humid summers and generally mild to cool winters.