Physical Characteristics. Polk County is in central Florida, east of the Tampa-St. Petersburg region, and is bordered by Sumter, Osceola, Highlands, Hardee, Hillsborough, and Pasco counties. The county has 1823.13 square miles of land and 187.20 square miles of water for a total of 2010.33 square miles. The average January temperature is 61.1 degrees fahrenheit, and the average August temperature is 81.8 degrees fahrenheit. The average annual rainfall is 49.21 inches.
History. Polk County was established in 1861 from portions of Brevard and Hillsborough counties and named for James Knox Polk, 11th president of the U.S.
