Physical Characteristics. St. Johns County is in northeast Florida and is bordered by the Atlantic Ocean and by Duval, Clay, Putnam, and Flagler counties. The county has 617.28 square miles of land and 55.30 square miles of water for a total of 672.58 square miles. The average January temperature is 57.1 degrees fahrenheit, and the average August temperature is 80.7 degrees fahrenheit. The average annual rainfall is 48.25 inches.
History. St. Johns County was established in 1821 as one of Florida's original two counties, the other being Escambia. The county was named for the St. Johns River. In 1565 Pedro Menendez de Aviles founded a settlement at St. Augustine. The town, continuously settled since that time, and the nearby Castillo de San Marcos, attract thousands of visitors each year.
