Extreme Heat

Temperatures that hover 10 degrees or more above the average high temperature for the region and last for several weeks are defined as extreme heat. Humid or muggy conditions, which add to the discomfort of high temperatures, occur when a "dome" of high atmospheric pressure traps hazy, damp air near the ground. Excessively dry and hot conditions can provoke dust storms and low visibility. Droughts occur when a long period passes without substantial rainfall. A heat wave combined with a drought is a very dangerous situation.

 

A heat wave is an extended period of extreme heat, and is often accompanied by high humidity. These conditions can be dangerous and even life-threatening for humans who don't take the proper precautions. Heat kills by pushing the human body beyond its limits. In extreme heat and high humidity, evaporation is slowed and the body must work extra hard to maintain a normal temperature.

 

Most heat disorders occur because the victim 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 succumb to extreme heat.

 

Conditions that can induce heat-related illnesses include stagnant atmospheric conditions and poor air quality. Consequently, people living in urban areas may be at greater risk from the effects of a prolonged heat wave than those living in rural areas. Also, asphalt and concrete store heat longer and gradually release heat at night, which can produce higher nighttime temperatures known as the "urban heat island effect."

 

Learn more about extreme heat preparedness here.

During extreme heat....

  • Have an Emergency Supply Kit and Household Disaster Plan in place.
  • 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.
  • Consider spending the warmest part of the day in public buildings such as libraries, schools, movie theaters, shopping malls, and other community facilities. Circulating air can cool the body by increasing the perspiration rate of evaporation.
  • Eat well-balanced, light, and regular meals. Avoid using salt tablets unless directed to do so by a physician.
  • Drink plenty of water. Persons who have epilepsy or heart, kidney, or liver disease; are on fluid-restricted diets; or have a problem with fluid retention should consult a doctor before increasing liquid intake.
  • Limit intake of alcoholic beverages.
  • Dress in loose-fitting, lightweight, and light-colored clothes that cover as much skin as possible.
  • Protect face and head by wearing a wide-brimmed hat.
  • Check on family, friends, and neighbors who do not have air conditioning and who spend much of their time alone.
  • Never leave children or pets alone in closed vehicles.
  • Avoid strenuous work during the warmest part of the day. Use a buddy system when working in extreme heat, and take frequent breaks.

Terms

Familiarize yourself with these terms to help identify extreme heat hazards.

  • Heat Wave
    Prolonged period of excessive heat, often combined 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. Exposure to full sunshine can increase the heat index by 15 degrees.
  • Heat Cramps
    Muscular pains and spasms due to heavy exertion. Although heat cramps are the least severe, 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. Blood flow to the skin increases, causing blood flow to decrease to the vital organs. This results in a form of mild shock. If not treated, the victim’s condition will worsen. 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 produces sweating to cool the body, stops working. The body temperature can rise so high that brain damage and death may result if the body is not cooled quickly.
  • Sun Stroke
    Another term for heat stroke.