Heat Safety

When most think of dangerous or lethal weather, phenomena such as tornadoes, hurricanes, floods, and blizzards typically come to mind. But what about heat? In the United States, heat is the #1 weather-related killer.


How Heat Affects the Body

Human bodies dissipate heat by varying the rate and depth of blood circulation, by losing water through the skin and sweat glands, and-as the last extremity is reached-by panting, when blood is heated above 98.6 degrees. The heart begins to pump more blood, blood vessels dilate to accommodate the increased flow, and the bundles of tiny capillaries threading through the upper layers of skin are put into operation. The body’s blood is circulated closer to the skin’s surface, and excess heat drains off into the cooler atmosphere. At the same time, water diffuses through the skin as perspiration. The skin handles about 90 percent of the body’s heat dissipating function.

Sweating, by itself, does nothing to cool the body, unless the water is removed by evaporation-and high relative humidity retards evaporation. The evaporation process itself works this way: the heat energy required to evaporate the sweat is extracted from the body, thereby cooling it. Under conditions of high temperature (above 90 degrees) and high relative humidity, the body is doing everything it can to maintain 98.6 degrees inside. The heart is pumping a torrent of blood through dilated circulatory vessels; the sweat glands are pouring liquid-including essential dissolved chemicals, like sodium and chloride-onto the surface of the skin.


Heat Disorders

During extremely hot and humid weather, your body’s ability to cool itself is challenged. When the body heats too rapidly to cool itself properly, or when too much fluid or salt is lost through dehydration or sweating, body temperature rises and you or someone you care about may experience a heat-related illness.

Heat Cramps

Heat cramps may be the first sign of heat-related illness and may lead to heat exhaustion or stroke.SYMPTOMS:

  • Painful muscle cramps and spasms, often in legs and abdomen.
  • Heavy sweating.


  • Apply firm pressure on cramping muscles or gently massage to relieve spasm.
  • Give sips of water unless victim complains of nausea, then stop giving water.

Heat Exhaustion


  • Heavy sweating
  • Weakness
  • Cool, pale, clammy skin
  • Fast, weak pulse
  • Muscle cramps
  • Dizziness
  • Nausea or vomiting
  • Fainting


  • Move person to cooler environment
  • Lay person down and loosen clothing
  • Apply cool, wet cloths to as much of the body as possible
  • Fan or move victim to an air-conditioned room
  • Offer sips of water
  • If person vomits more than once, seek immediate medical attention

Heat Stroke


  • Altered mental state, unconsciousness, or fainting
  • Body temperature over 103 F
  • Hot, red, dry or moist skin
  • One or more of the following: throbbing headache, confusion, nausea, dizziness, shallow breathing
  • Rapid and strong pulse


  • CALL 911 IMMEDIATELY. This is a medical emergency.
  • Move person to cooler environment
  • Reduce victim’s body temperature with cool cloths or bath
  • Do NOT give fluids


Heat Index

Heat Index measures how hot it really feels by factoring in relative humidity with actual air temperature. To find the heat index temperature, use the chart above.

CAUTION means that fatigue is possible with prolonged exposure and/or physical activity.

EXTREME CAUTION means sunstroke, muscle cramps, and/or heat exaustion are possible with prolonged exposure and/or physical activity.

DANGER indicates that sunstroke, muscle cramps, and heat exhaustion are likely. Heat stroke is also possible with prolonged exposure and/or physical activity.

EXTREME DANGER means heat stroke is likely, even with limited exposure and minimal physical activity.


Warnings, Watches, & Advisories

Excessive Heat Warning-issued when a life-threatening excessive heat event is already occurring or expected in the next 36 hours.

Excessive Heat Watch-issued when conditions are favorable for an excessive heat event within the next 24 to 72 hours.

Excessive Heat Advisory-issued when an excessive heat event is occurring or expected in the next 36 hours.


Beat the Heat-Prevention

  • Reduce, eliminate or reschedule strenuous activities until the coolest time of the day. Children, seniors and anyone with health problems should stay in the coolest available place, not necessarily indoors.
  • Dress for summer. Wear lightweight, loose lifting, light-colored clothing to reflect heat and sunlight.
  • Eat light, cool, easy-to-digest foods such as fruit or salads.
  • Drink plenty of water (not very cold), non-alcoholic and decaffeinated fluids, even if you don’t feel thirsty. If you on a fluid restrictive diet or have a problem with fluid retention, consult a physician before increasing consumption of fluids.
  • Use air conditioners or spend time in air-conditioned locations such as malls and libraries.
  • Use portable electric fans to exhaust hot air from rooms or draw in cooler air.
  • Do not direct the flow of portable electric fans toward yourself when room temperature is hotter than 90°F. The dry blowing air will dehydrate you faster, endangering your health.
  • Minimize direct exposure to the sun. Sunburn reduces your body’s ability to dissipate heat.
  • Take a cool bath or shower.
  • Do not take salt tablets unless specified by a physician.
  • Check on older, sick, or frail people who may need help responding to the heat. Each year, dozens of children and untold numbers of pets left in parked vehicles die from hyperthermia.  Keep your children, disabled adults, and pets safe during tumultuous heat waves.


Sources/Additional Info:



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