A review of te existing literature is made and a summary of comfort indexes over the past 75 years is made, with shortfalls noted. The new Summer Simmer Index is then presented. It is derived from studies by the American Society of Heating and Refrigeration Engineers and confirmed by tests and analyses done at Kansas State University. Unlike the index derived from those studies, however, it meets all scientific and subjective requirements and relates to a dry environment. As such, the new Summer Simmer Index is the only index which uses results of proven physiological models and human tests over the past 75 years and relates numerical values of temperature-humidity equivalent temperatures to a dry environment for general public acceptance. By doing so the index, like wind chill, provides a meaningful and realistic temperature equivalent that can not only be used as an indication as to how hot it feels, but also as a readily identifiable warning for individuals subject to the physiolog