Abstract: A device for determining the ambient heat index and communicating that information to a user, the device having a housing member, a control mechanism, and a power source. The control mechanism includes a microprocessor, an air temperature measuring device, and a relative humidity measuring device, wherein the air temperature measuring device and the relative humidity measuring device respectively determine the user's ambient air temperature and ambient relative humidity and communicate that information real time to the microprocessor for determination of the heat index. The control mechanism has a display mechanism for displaying the heat index, and another display mechanism for displaying the ambient temperature and the ambient relative humidity. Switches permit manual operation of activation of the display mechanisms.