The heat is no joke and this year, it's impacting a large portion of the U.S. Here's what to know about heat stroke, ...

Heat stroke is more dangerous than heat exhaustion and may occur, for example, when you engage in physical activities in a hot environment or when heat exhaustion is not properly treated.

If someone is experiencing heat stroke, you should call 911 immediately. Serious cases of heat stroke can be fatal as it is an extreme medical emergency, according to WebMD.

Unlike with heat exhaustion, the skin during a heat stroke becomes hot and dry to the touch, meaning the body has begun shutting down. The bottom line: a heat stroke is a 911 call every time.

Find shade, rest, and use cool, damp cloths to lower your body temperature. If you see signs of heat stroke in someone else, call for medical help. Be careful with fans.