Bear Grylls has written about how to avoid hypothermia and frostbite, but the condition called hyperthermia, where the body overheats, is just as dangerous.  Videos by Outdoors So what is hyperthermia? The average normal body temperature is generally 98.6°F (37°C), while it can vary from 97°F (36.1°C) to 99°F (37.2°C) or more, depending on your […]