Extreme Heat

Heat can kill people because it pushes the human body past what it can handle. In extreme heat and high humidity, water evaporation is slowed and the body must work extra hard to keep a normal temperature.

Most heat problems occur because the person has been overexposed to heat or has over-exercised for his or her age and physical condition. Older adults, young children and those who are sick or overweight are more likely to give in to extreme heat.

Conditions that can bring on heat-related illnesses include still atmospheric conditions and poor air quality. People who live cities may be at greater risk from the effects of a long heat wave than those living in rural areas. Asphalt and concrete store heat longer and slowly release heat at night. This can make temperatures rise at night in a city, called the "urban heat island effect."

A heat wave is a long time of extreme heat. It is often with high humidity. These conditions can be dangerous and even life-threatening for people who don’t do what they ought to do to keep themselves safe.

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Ways to get ready for long periods of heat:

  • You should make an emergency kit and family communications plan.
  • Put in window air conditioners snugly; insulate if needed.
  • Check air-conditioning ducts for proper insulation.
  • Put in short-term window reflectors for use between windows and drapes, such as aluminum foil-covered cardboard, to reflect heat back outside.
  • Weather-strip doors and sills to keep cool air in.
  • Cover windows that receive morning or afternoon sun with drapes, shades, awnings or louvers. Outdoor awnings or louvers can lower the heat that comes in a home by up to 80 percent.
  • Keep storm windows up all year.
  • Listen to local weather forecasts. Stay alert about upcoming temperature changes.
  • Know those in your neighborhood who are elderly, young, sick or overweight. They are more likely to be harmed by excessive heat and may need help.
  • People living in cities may be at more risk from the long periods of heat than people living in rural areas.
  • Get trained in first aid to learn how to treat heat-related emergencies.

Know the Terms

Learn what these words mean to help you know about extreme heat hazards.

Heat Wave - Long period of excessive heat, often shared with excessive humidity.

Heat Index - A number in degrees Fahrenheit (F) that tells how hot it feels when relative humidity is added to the air temperature. Being in full sunshine can raise the heat index by 15 degrees.

Heat Cramps - Muscular pains and spasms caused by do a lot of heavy actions. Heat cramps are not the worst. They are often the first signal that the body is having trouble with the heat.

Heat Exhaustion - Typically occurs when people exercise heavily or work in a hot, humid place where body fluids are lost through heavy sweating. There is more blood flow to the skin. This causes blood flow to decrease to the main organs. This causes a form of mild shock. If not treated, the person’s problems will get worse. Body temperature will keep rising, and the victim may suffer heat stroke.

Heat Stroke - A life-threatening condition. The victim’s temperature control system, which makes sweating to cool the body, stops working. The body temperature can rise so high to cause brain damage and death if the body is not cooled quickly.

Sun Stroke - Another way to say heat stroke.

Excessive Heat Watch – There is a good chance 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).

What you should do if the weather is extremely hot:

  • Listen to NOAA Weather Radio for key updates from the National Weather Service (NWS).
  • Never leave children or pets alone in closed vehicles.
  • Stay indoors as much as possible and limit exposure to the sun.
  • Stay on the lowest floor out of the sunshine if air conditioning is not available.
  • Postpone outdoor games and activities.
  • Think about spending the warmest part of the day in public buildings such as libraries, schools, movie theaters, shopping malls and other community places. Cool air can cool the body by raising the perspiration rate of water evaporation.
  • Eat well-balanced, light and regular meals. Avoid using salt tablets unless told to do so by a doctor.
  • Drink plenty of water; even if you do not feel thirsty. Stay away from drinks with caffeine. People who have epilepsy or heart, kidney, or liver disease; are on fluid-restricted diets; or have a problem with fluid retention should talk with a doctor before increasing liquid intake.
  • Limit the number of alcoholic beverages you drink.
  • Dress in loose-fitting, lightweight and light-colored clothes that cover a lot of skin. Try not to wear dark colors because they absorb the sun’s rays.
  • Protect face and head by wearing a wide-brimmed hat.
  • Avoid hard work during the warmest part of the day. Use a buddy system when working in extreme heat, and take breaks often.
  • Check on family, friends and neighbors who do not have air conditioning and who spend much of their time alone.
  • Stay away from extreme temperature changes.
  • Check on your animals often to make sure that they are not suffering from the heat.
  • Go to a designated public shelter if your home loses power during periods of extreme heat. Text SHELTER + your ZIP code to 43362 (4FEMA) to find the nearest shelter in your area (example: shelter 12345). You can enter your zip code at www.211.org to find cooling-off centers.

First Aid for Heat-Induced Illnesses

Extreme heat brings with it the possibility of heat-induced illnesses. The following table lists these illnesses, their symptoms, and the first aid treatment.



First Aid


Skin redness and pain, possible swelling, blisters, fever, headaches

Take a shower using soap to remove oils that may block pores, preventing the body from cooling naturally.

Apply dry, sterile dressings to any blisters, and get medical attention.

Heat Cramps

Painful spasms, usually in leg and abdominal muscles; heavy sweating

Get the victim to a cooler location.

Lightly stretch and gently massage affected muscles to relieve spasms.

Give sips of up to a half glass of cool water every 15 minutes. (Do not give liquids with caffeine or alcohol.)

Discontinue liquids, if victim is nauseated.

Heat Exhaustion

Heavy sweating but skin may be cool, pale, or flushed. Weak pulse. Normal body temperature is possible, but temperature will likely rise. Fainting or dizziness, nausea, vomiting, exhaustion, and headaches are possible.

Get victim to lie down in a cool place.

Loosen or remove clothing.

Apply cool, wet clothes.

Fan or move victim to air-conditioned place.

Give sips of water if victim is conscious.

Be sure water is consumed slowly.

Give half glass of cool water every 15 minutes.

Discontinue water if victim is nauseated.

Seek immediate medical attention if vomiting occurs.

Heat Stroke
(a severe medical emergency)

High body temperature (105+); hot, red, dry skin; rapid, weak pulse; and rapid shallow breathing. Victim will probably not sweat unless victim was sweating from recent strenuous activity. Possible unconsciousness.

Call 9-1-1 or emergency medical services, or get the victim to a hospital immediately. Delay can be fatal.

Move victim to a cooler environment.

Removing clothing

Try a cool bath, sponging, or wet sheet to reduce body temperature.

Watch for breathing problems.

Use extreme caution.

Use fans and air conditioners.


If you need more details about any of these areas, use the sources below to help.

National Weather Service

Related Websites

Listen to Local Officials

Learn about the emergency plans that have been made in your area by your state and local government. In any emergency, always listen to the orders given by local emergency management officials.