Heat Stress Indices are equations that integrate all or some atmospheric variables (e.g. temperature, relative humidity, wind speed, solar radiation), directly or indirectly, to produce a number for thermal stress on humans for a particular environment. There are a large number of equations that have been developed which range from simple equations that may ignore some basic factors (e.g. wind effects on thermal loading, fixed contribution from solar heating) to complex equations that attempt to incorporate all variables. Each equation is evaluated for a particular use, as well as considering the ease of use and reliability of the results. The meteorology group at the Dryden Flight Research Center has enhanced the American College of Sports Medicine equation to represent the specific environment of the Mojave Desert. The Dryden Heat Stress equation has been vetted and implemented as an automated notification to the entire facility for the safety of all personnel and visitors.