Impact of Heat Waves

Storm Encyclopedia

The Weather Channel uses the following criteria for a heat wave: a minimum of ten states with 90 degree plus temperatures and the temperatures must be at least five degrees above normal in parts of that area for at least two days or more.

The intensity of the heat necessary to be called a heat wave varies with the location.

A period of hot, humid weather in Chicago, Detroit, or New York could be considered normal in Atlanta, New Orleans, or Houston. This is because sporadic hot weather where it is less common is more taxing on the population than prolonged heat and humidity where it is typical.

Since the stress of heat is dependent on geographic area and human tolerances of the climate, heat-related problems are more likely to occur earlier in the summer, like in June, than later in the season, like in August. Northern and urban areas are not easily adaptive to occasional heat waves.

Heat-Related Problems

The heat index is not the actual air temperature, but rather, the combination of air temperature and humidity that gives a description of how the temperature feels.

Apparent Temperature Readings

• Caution - 85 to 94°F - physical activity may cause fatigue
• Extreme Caution - 95 to 105°F - possible heat cramps and/or heat exhaustion with prolonged exposure
• Danger - Above 105°F - possible heat stroke with prolonged exposure; heat exhaustion and heat cramps likely

The body's response to overexposure to high temperature and high humidity could be in the form of the following:

• Severe Sunburn - reduces the skin's ability to release excess heat, making the body more susceptible to heat-related illness
•  Heat Cramps - muscle pains and spasms, usually of the extremities, caused by heavy exertion, which triggers loss of water through heavy perspiration
• Heat Exhaustion - a mild form of shock marked by heavy sweating, weakness, cold, clammy skin, a weak pulse, fainting and vomiting
• Heat Stroke (also called Sunstroke) - a truly life-threatening condition in as an individual's body temperature is greater than 105 degrees, the skin is hot and dry, there is a rapid and irregular pulse, perspiration has stopped, and one has lost consciousness