This element was computed using data from the National Climatic Data Center's Surface Airways Hourly (TD-3280) database (NOAA, 2000a). The original data is in whole degrees Fahrenheit. This element is computed to tenths of a degree Fahrenheit. The mean monthly values were computed by taking the 30-year mean of the monthly means. The monthly means were computed from the daily values. The mean annual value was computed by taking the 30-year mean of the yearly means. The yearly means were computed by averaging their 12 monthly mean values. Data extracted for Arizona and 25 mile buffer.