Temperatures in the 80's and 90's combined with high levels of humidity can reach the danger zone, which combined with intense exercise can increase your chances for heat exhaustion or heat stroke. When weather conditions reach the danger zone, no one should exercise. Wait until conditions improve. The symptoms of heat exhaustion include a weak and rapid pulse, cold, clammy and pale skin, headache, dizziness, and generalized weakness. If you experience these symptoms while exercising, stop and lie down in a cool spot.
Heat stroke is much more serious.
The skin becomes hot and dry, sweating is absent and the person may complain of headache, dizziness, faintness and abdominal distress. They may be confused and lethargic. Breathing may be rapid and weak, the pulse rapid, the blood pressure is usually low. The body temperature may be greater than 106 degrees. Immediate medical attention is required if symptoms appear, as coma and shock may occur and death may ensue.