Medical Services Sports Medicine Heat Index Find a Location Find a Doctor Sports Medicine Menu Sports Medicine Athletic Training Athletic Trainer Tips Back On Track Aquatic Therapy Injury Clinics Heat Index ImPACT Test Medical Motion On the Run with Stacey Resources FAQs Be Aware of the Heat Index When practicing or working out outdoors, it is important to be aware of what the heat index is. According to the National Weather Service, The 'Heat Index' is a measure of how hot weather "feels" to the body. Heat index is calculated by looking at the relative humidity at the site of the activity and the temperature. Outdoor activity should be modified or eliminated based on the heat index. Click here to download a printable Heat Index chart (taken from the KMA/KHSAA website) to determine how safe it is for outdoor activities. To determine the Heat Index for your activity, enter the relative humidity and temperature in Fahrenheit into the calculator on this page.