Extreme Heat and Your Health
August 24, 2022
Nick Bradford

Did You Know?

  • Heatwaves have become more frequent and cold waves have become less frequent over the past century in the US.
  • Annual average US temperatures are expected to increase 3 and 10°F by the end of the century, depending on future emissions and other factors. 
  • From 1999 through 2009, extreme heat exposure caused or contributed to more than 7,800 deaths in the United States.

Extreme heat is a leading cause of weather-related deaths in the United States. Heat-related deaths are often a result of heat stroke and related conditions, but also occur in people with cardiovascular disease, respiratory disease and cerebrovascular disease.

The number of extreme heat events in the United States continues to rise and climate projections indicate that these events will be more frequent and intense in the coming decades. From 1901 to 1970, the average surface temperature in the United States rose at an average rate of 0.13°F per decade. Since the late 1970s, this rate has increased to between 0.26 and 0.43°F per decade. According to EPA, a changing climate is expected to result in increases in extreme temperatures.

If greenhouse gas emissions are not reduced over the course of the 21st century (reference), the hottest days of the year in the Mountain West are projected to be up to 14°F hotter than today; the hottest days in many parts of the Midwest and Northeast are projected to be 7-10°F hotter. If greenhouse gas emissions are reduced over the 21st century (mitigation), EPA projects that the hottest days will be no more than 4°F hotter for all regions of the country.

Preventative actions, such as early warning systems and land use changes to reduce the urban heat island effect, may reduce heat-related sickness and death. But, it's important to remember that everyone is not equally at risk. Children, people 65 years and older, people who are sick, and people without access to air conditioning are at greater risk of heat-related illnesses.

What you can do

Learn More

  • Discover more about how future increases in temperature will impact human health in USGCRP'S Climate and Health Assessment's "Temperature-Related Death and Illness" section
  • The Figure below shows how annual average temperatures have changed in different parts of the US from 1904 to 1914. 


Rate of US Temperature Change
  • The diagram below predicts what future changes in temperature will be with and without global greenhouse gas mitigation. 


Temperature Change