Wilmington is a city in and the county seat of Clinton County, Ohio, United States. The population was 12,660 at the 2020 census. At city entrances from state routes, county roads, and U.S. highways, the city slogan of "We Honor Our Champions" is seen, accompanied by signs that highlight various athletic accomplishments from Wilmington individuals and teams. The city features a weather forecast office of the National Weather Service, which serves all of Southwestern Ohio and portions of Kentucky and Indiana.