Heat Wave

A heat wave is defined by the ARC as a ‘prolonged period of excessive heat and humidity’. This is a useful definition because it emphasizes the combined effects of both air temperature and humidity. 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 [FEMA]. As well as significant loss of life, heat waves can also cause significant economic losses through livestock/crop losses and damage to roads, railways, bridges, power reticulation infrastructure, electrical equipment, and so on. 


  • Never leave children or pets alone in enclosed vehicles.
  • Take frequent breaks if working outdoors.
  • Check on family, friends and neighbors who do not have air conditioning, who spend much of their time alone or who are more likely to be affected by the heat.
  • Check on animals frequently to ensure that they are not suffering from the heat. Ensure they have water and a shady place to rest.
  • Eat small meals and eat more often. Avoid foods that are high in protein which increase metabolic heat.
  • Avoid extreme temperature changes.
  • Wear loose-fitting, lightweight, light-colored clothing.
  • Slow down and avoid strenuous activity. If this cannot be avoided, do it during the cooler parts of the day e.g. between 4.00 and 7.00 am.
  • Stay indoors as much as possible and stay out of the sun. If air conditioning is not available, stay on the lowest floor. Try to go to a public building with air conditioning, such as a shopping center, each day for several hours. Whilst electric fans do not cool the air, they do help sweat to evaporate, which in turn cools the body. Ensure that the building you are in has adequate ventilation.
  • Drink plenty of water regularly. Avoid drinks with alcohol or caffeine in them. They may make you feel good briefly, but they make the effects of the heat on the body worse. This is especially true of beer which dehydrates the body.

[Source: ARC]



Consider creating a or revising your current workplace’s Business Continuity Program.

Excessive heat can lead to sunburn, heat cramps, heat exhaustion and heat stroke. To help avoid problems, stay hydrated by drinking plenty of fluids and limit drinks with caffeine or alcohol. The main factor involved in the degree to which we feel uncomfortable in such conditions is not so much because we feel hot, but rather we sense how difficult it has become for us to lose body heat at the rate necessary to keep our inner body temperature close to 37 °Celsius /99° Fahrenheit.

The body responds to this stress caused by heat progressively through three stages:

• heat cramps – muscular pains and spasms caused by heavy exertion. Although heat cramps are the least severe stage they are an early 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 a decrease of flow to vital organs. This results in mild shock with the symptoms of cold, clammy and pale skin together with fainting and vomiting. If not treated the victim may suffer heat stroke;

 heat stroke – is life threatening. The victims temperature control system, which produces sweating to cool the body, stops working. The body temperature may exceed 40.6 °C/ 105° F potentially causing brain damage and death if the body is not cooled quickly.

[Source: ARC]

Heat disorder symptoms and first aid.





Redness and pain. In severe cases swelling of skin, blisters, fever, headaches.


Ointments for mild cases if blisters appear and do not break. If breaking occurs, apply dry sterile dressing. Serious, extensive cases should be seen by physician.



Painful spasms usually in muscles of legs and abdomen possible. Heavy sweating.


get them to a cooler place, have them rest, lightly stretch the affected muscle and replenish their fluids with a half a glass

Firm pressure on cramping muscles, or gentle massage to relieve spasm. Give sips of water. If nausea occurs, discontinue use.


Heavy sweating, weakness, skin cold, pale and clammy. Pulse thready. Normal temperature possible. Fainting and vomiting.


Get victim out of sun to a cooler place. Lay down and loosen clothing. Spray the person with water or apply cool, wet cloths or towels to the skin.  Fan or move victim to air conditioned room If they are conscious, give small amounts of cool water to drink. If nausea occurs, discontinue use Watch for changes in condition. If the person refuses water, vomits or begins to lose consciousness, call the local emergency number.


(or sunstroke)

High body temperature (106°

F. or higher). Hot, red skin which may be dry or moist. Vomiting. Rapid and strong pulse. Possible unconsciousness.



Move the victim to a cooler environment.  Quickly cool the person’s body by immersing them up to their neck in cold water if possible. Otherwise, douse or spray the person with cold water, or cover the person with cold, wet towels or bags of ice. Use extreme caution. Remove clothing, use fans and air conditioners. If temperature rises again, repeat process. Do not give fluids. Call the local emergency number immediately if some shows signs of heat stroke.

[Source: NOAA, ARC, FEMA]

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 forecasting to meet or exceed locally defined warning criteria for at least 2 days (daytime highs=40-45° Celsius/105-110° Fahrenheit).

Heat Advisory: Heat Index values are forecasting to meet locally defined advisory criteria for 1 to 2 days (daytime highs=37-40° Celsius/100-105° Fahrenheit). 

[Source: ARC]