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Extreme Heat Events: What Are They and How to Stay Healthy During One

By Melissa Kluczynski, MS


Every summer more than 65,000 people in the U.S. visit the emergency room due to acute heat-related illness. Extreme heat was the leading cause of weather-related deaths in the U.S. from 2000 to 2009; and between 1999 to 2009 extreme heat exposure caused or contributed to 7,800 deaths in the U.S. Due to climate change, extreme heat events are expected to increase in the U.S. meaning that the number of heat-related illnesses and deaths will likely increase too. However, heat-related illnesses and deaths are preventable. Read on to find out more about extreme heat events and how to stay healthy during one.


What is an Extreme Heat Event? Extreme heat is when the temperature and/or humidity is much higher than normal. Extreme heat varies based on different factors including geographic location, weather conditions (e.g., cloud cover), and time of year. “Urban heat islands” refer to cities that experience longer and more severe periods of extreme heat compared to rural and suburban areas. Cities tend to be 10° warmer than rural and suburban areas because concrete and asphalt absorbs and holds heat, tall buildings reduce the flow of cool air, and lack of trees and vegetation that provide shade.


What are the Health Consequences of Extreme Heat? The most common health effects caused by extreme heat are: heat cramps (muscle pains or spasms that happen during heavy exercise), heat exhaustion (occurs after several days of exposure to high temperatures and not enough fluids), and heat stroke (life-threatening illness that occurs when body temperature rises above 106° F). Heat exhaustion and heat stroke are serious conditions that require emergency treatment. Learn more about the signs and symptoms of heat-related illness here.