Abstract: A method and apparatus for monitoring heat stress, wherein the apparatus may include a skin surface temperature probe and heart rate probe that do not require direct physical contact to a user's skin. The method includes the steps of: measuring a plurality of physiological parameters including at least heart rate and skin surface temperature of a user; calculating at least body core temperature of the user as a function of the plurality of physiological parameters using a predetermined algorithm; comparing at least heart rate and body core temperature to corresponding maximum thresholds; and alerting the user when at least one of heart rate and body core temperature exceeds the corresponding maximum threshold.