Extreme Heat

The Tracking Network collects data on heat-related deaths and illnesses throughout the United States and provides information so people can protect themselves.

Heat-related Deaths

Extreme heat events, or heat waves, are a leading cause of extreme weather-related deaths in the United States. The number of heat-related deaths is rising. For example, in 1995, 465 heat-related deaths occurred in Chicago. From 1999 to 2010, a total of 7,415 people died of heat-related deaths, an average of about 618 deaths a year.

Heat Stress

Heat stress is heat-related illness caused by your body's inability to cool down properly. The body normally cools itself by sweating. But under some conditions, sweating just isn't enough. In such cases, a person's body temperature rises rapidly. Very high body temperatures may damage the brain or other vital organs.

Several factors affect the body's ability to cool itself during extremely hot weather. When the humidity is high, sweat will not evaporate as quickly, preventing the body from releasing heat quickly. Other conditions related to risk include age, obesity, fever, dehydration, heart disease, mental illness, poor circulation, sunburn, and prescription drug and alcohol use.

Heat stress ranges from milder conditions like heat rash and heat cramps, to the most common type, heat exhaustion. The most serious heat-related illness is heat stroke. Heat stroke can cause death or permanent disability if emergency treatment is not provided.

Read more about heat stress.

Risk Factors

Anyone can develop heat stress. However, the following groups of people have higher risks for experiencing heat stress or heat-related death:

• Infants and children up to four years of age,
• People 65 years of age and older,
• People who are overweight, and
• People who are ill or on certain medications

More information for specific groups

Prevention

Heat-related death or illnesses are preventable if you follow a few simple steps.

• Stay in an air-conditioned area during the hottest hours of the day. If you don't have air conditioning in your home, go to a public place such as a shopping mall or a library to stay cool. Cooling stations and senior centers are also available in many large cities for people of all ages.
• Wear light, loose-fitting clothing.
• Drink water often. Don't wait until you are thirsty.
• Avoid unnecessary hard work or activities if you are outside or in a building without air-conditioning.
• Avoid unnecessary sun exposure. When in the sun, wear a hat, preferably with a wide brim.

Air conditioning is the strongest protective factor against heat-related illness. Exposure to air conditioning for even a few hours a day will reduce the risk for heat-related illness.

Read more prevention tips.

Infographic