Comparison of weather service heat indices using a thermal model

Abstract The US and Canadian weather service heat indices were evaluated to determine if one is a better predictor of the risk of heat injury. Heat index values were compared to the rectal temperature predicted by a heat-balanced-based thermal model to determine if there was a statistically significant relation between the heat index values and predicted rectal temperature. R 2 values ranged between 0.96 and 0.99 for the conditions investigated. Equations that predicted rectal temperature from the heat indices are presented. Both indices are highly correlated with predicted rectal temperatures.