Extreme Heat



Extreme heat can be very dangerous. In extreme heat and high humidity, evaporation is slowed and the human body must work extra hard to maintain a normal temperature. This can push the body beyond its limits. In the United States each year, 400 people die from heat-related complications, more than from any other natural disaster.



Stay informed, and know heat terminology:

  • Heat Wave—An extended period of extreme heat, usually combined with excessive humidity.

  • Heat Index—A number of degrees in Fahrenheit (F) added to the air temperature that tells how hot it feels with the relative humidity.

  • Excessive Heat Watch—Conditions are favorable for an excessive heat event to meet or exceed local Excessive Heat Warning criteria in the next 24 to 72 hours.

  • Excessive Heat Warning—Heat Index values are forecast to meet or exceed locally defined warning criteria for at least two days (daytime highs=105-110° Fahrenheit).

  • Heat Advisory—Heat Index values are forecast to meet locally defined advisory criteria for one to two days (daytime highs=100-105° Fahrenheit).

  • Listen to local weather forecasts and stay aware of upcoming temperature changes.

  • Be aware that people living in urban areas may be at greater risk from the effects of a prolonged heat wave than are people living in rural areas, due to stagnant and poor air quality, as well as stored heat in asphalt and concrete.

  • Make a plan to keep you and your family safe from the effects of extreme heat.

  • Make sure you have a fan, snugly fit window air conditioner, or something to circulate air in extreme heat as many heat-related deaths can be attributed to stagnant atmospheric conditions or poor air quality.

  • Insulate air ducts and weather-strip doors and sills to keep cool air in.

  • Cover windows that receive morning or afternoon sun with drapes, shades, etc.

  • Keep storm windows up year round.

  • Understand that elderly, young, sick, and overweight individuals are at greater risk, and learn first aid to help treat heat-related emergencies.

  • Build an emergency kit

  • Slow down and don’t do anything too strenuous.

  • Stay inside as much as possible.

  • Never leave children or pets alone in closed vehicles.

  • If air conditioning is not available in your home, stay on the lowest level or go to a public building with air conditioning.

  • If you stay in your home without air conditioning, make sure there is a way, such as a fan, to circulate the air around you.

  • Drink lots of water, even if you don’t feel thirsty.

  • Eat well-balanced, light, and regular meals.

  • Avoid alcohol, caffeine, and salt.

  • Wear loose-fitting, lightweight, and light-colored clothing.

  • Be aware that a power outage or drought can result from a heat wave.

  • Per MARADMIN 111/15, practice buddy aid: "If someone looks ill or otherwise unfit to participate, ensure those individuals report to medical department personnel for assessment." 


Keep a lookout for possible heat emergencies:

  • Heat cramps—Muscle spasms and aches from heavy exertion in extreme heat. They are usually the first sign of heat-related complications.

  • Heat exhaustion—A form of mild shock that results from insufficient body fluids due to extreme heat and excessive exercising. The blood flow to the skin increases, decreasing blood flow to vital organs and raising the body temperature, increasing the risk of a heat stroke.

  • Heat stroke/sun stroke—The body’s temperature control system stops working, causing body temperature to rise so high (103˚F or more) that there may be brain damage or death.

  • If you experience or observe any of the above conditions, seek medical attention immediately.


Set your own course through any hazard: stay informed, make a plan, build a kit. Live Ready Marine Corps.