Core body temperature

Core body temperature is the heat of the body's deep organs. In heat stroke, the body can no longer control its temperature. NIOSH says body temperature can rise to 106°F or higher within 10 to 15 minutes. It also says heat stroke can cause permanent disability or death without emergency treatment.

Heat stroke is always a 911 emergency. Signs include confusion, slurred speech, seizures and loss of consciousness. Earlier warning signs show up as heat exhaustion. Learn the difference in our heat exhaustion vs heat stroke guide. See also heat stroke and heat stress.