Physical Characteristics. Indian River County is on the Atlantic coast between the Melbourne-Titusville and Ft. Pierce areas. It is bordered by Brevard, Osceola, Okeechobee, and St. Lucie counties. The county has 497.06 square miles of land and 42.60 square miles of water for a total of 539.66 square miles. The average January temperature is 63.4 degrees Fahrenheit, and the average August temperature is 81.3 degrees Fahrenheit. The average annual rainfall is 52.84 inches.
History. Indian River County was established in 1925 from a portion of St. Lucie County and named for the Indian River.
