Wahiawa is a census-designated place (CDP) in Honolulu County, Hawaii, United States, on the island of Oahu. It is located in the Wahiawa District, on the plateau or "central valley" between the two volcanic mountains that comprise the island. In Hawaiian, wahi a w? means "place of noise", perhaps a reference to the fact that once upon a time, heavy surf on the distant coast could be heard here. The population was 17,821 at the 2010 census. According to the United States Census Bureau, the CDP has a total area of 2.4 square miles (6.2 km2), of which 2.1 square miles (5.5 km2) is land and 0.27 square miles (0.7 km2), or 11.34%, is water.