Heat related deaths are common, it doesn't even have to be that hot outside it's about your internal temp. There's three stages, heat cramps from dehydration then heat exhaustion which you willl sweat a lot, feel light headed, or even have headaches and vomiting. Then the last stage is heat stroke which can be lack of sweating, dry red skin, confusion, convulsions / seizures. But you will die if left untreated and even die if treated in some cases. Very unpleasant.