The Urban Heat Island and Local Temperature Variations in Orlando, Florida

Cities artificially alter local climates affecting economic and biological processes. This study examined air temperatures in Orlando’s urban canopy layer using a network of twenty-nine fixed-point stations from September 1999 to December 2001. Urban Heat Island (UHI) statistics were calculated using two stations that were representative of an urban and rural setting. Orlando’s UHI develops best on calm, clear nights during dry months: its maximum magnitude exceeds 8°C. Orlando’s UHI, however, is predominantly a nocturnal phenomenon with intense heat islands sometimes occurring during warm afternoons. These events are most likely attributable to isolated thundershowers. Local temperature variations between urban and rural extremes were examined by calculating environmental indices for all stations. The range in monthly cooling degree-day totals exceeded 100 degree days in six months of the thirty-six month study period. Heating degree totals and number of freezing hours were also highly variable.