The risk of a heat stroke can be reduced by observing precautions to avoid overheating and dehydration. Light, loose-fitting clothing will allow perspiration to evaporate. Wide-brimmed hats in bright color keep the sun from warming the head and neck; vents on a hat will allow perspiration to cool the head. Strenuous exercise should be avoided during daylight hours in hot weather; so should remaining in enclosed spaces (such as automobiles). People who must be outside should be aware that humidity and the presence of direct sunlight may cause the heat index to be 10 °C (18 °F) hotter than the temperature indicated by a thermometer.

In hot weather people need to drink plenty of liquids to replace fluids lost from sweating. Thirst is not a reliable sign that a person needs fluids. A better indicator is the color of urine. A dark yellow color indicates dehydration. While alcoholic beverages, tea, and coffee may help somewhat in restoring lost fluids, their diuretic effect in these situations is counterproductive. Water or sports drinks are more effective.