As summer heat intensifies across the U.S., the American Heart Association is warning that soaring temperatures don't just make people uncomfortable - they can put serious strain on the heart and increase the risk of life-threatening complications. Although tragic deaths from major disasters like hurricanes and tornados may get the most news coverage, extreme heat is actually the leading weather-related cause of death in the United States, according to the National Weather Service.
A report in the Journal of the American Medical Association found that more than 2,300 people died from heat exposure in the U.S. in 2023. Research published in the American Heart Association's journal Circulation projects that heat-related cardiovascular deaths could more than double in the coming decades.
"Heat forces the heart to work harder," said Manesh R. Patel, M.D., FAHA, volunteer president of the American Heart Association and chief of the division of cardiology at Duke Health. "When your body is trying to cool down, your heart rate increases and your blood vessels expand. For people with heart disease, and even those who are otherwise healthy, that added strain can become dangerous quickly."
When temperatures climb, the body sweats to cool itself, which can lead to fluid loss and dehydration. At the same time, the heart must pump more blood to regulate body temperature. Together, these changes can put significant stress on the cardiovascular system.
The American Heart Association recommends taking simple but important steps to stay safe: avoid peak heat hours between noon and 3 p.m., dress in lightweight light-colored clothing, stay hydrated with water, take breaks in shade or cool indoor spaces, and know the warning signs of heat exhaustion and heat stroke.
Heat exhaustion symptoms include headache, cool pale clammy skin, fast but weak pulse, dizziness or fainting, weakness or muscle cramps, and nausea or vomiting. If you experience these, slow down, move to a cooler place, cool down with cold water, and re-hydrate. Heat stroke is a medical emergency with symptoms including body temperature above 103°F, hot red dry or damp skin, rapid strong pulse, confusion, headache, or loss of consciousness. Call 9-1-1 immediately if these occur.
Physical activity remains essential for heart health, even in summer. Try walking, swimming, biking, or gardening, but shift exercise to early morning or evening hours when it's cooler, or move workouts indoors to air-conditioned spaces. Learn more about staying heart-healthy in the heat at heart.org.
