There are many potential signs of heat stroke. Rectal thermometer readings of 104 F (40 C) or higher are the main sign of heatstroke. A change in mental state or behavior. Heatstroke can result in slurred speech, confusion, delirium, agitation irritability, seizures, and coma. Sweating changes. The skin will feel hot and dry when you suffer from heatstroke in hot weather. The skin may feel slightly moist or dry in cases of heat stroke caused by strenuous exercise. Vomiting and nausea may occur. Increasing your body temperature may cause your skin to turn red. Rapid and shallow breathing may occur. Heat stress puts a great deal of strain on your heart, forcing it to work harder to cool your body. This may result in a significant increase in your pulse rate. You may feel a throbbing in your head.