Heat Stress Index
Building a U.S. Heat Stress Climatology
In 1998, Gaffen and Ross (1998 and 1999) compiled an apparent temperature climatology for 187 first-order U.S. weather stations. They calculated the 85th percentiles of daily maximum, minimum and average apparent temperatures over the 1961-1990 base period, for each station, which were then used as threshold values for identifying extreme heat stress conditions. The 85th percentile values have been shown to be closely correlated with weather related mortality statistics (Kalkstein and Davis 1989). Analyzing data for 1948-1995, Gaffen and Ross (1998) showed increases in the number of exceedances of these threshold values at most of the U.S. stations studied, with the largest increases in the eastern and western regions.
