As summer temperatures soar across the United States, the American Heart Association (AHA) is issuing a stark warning: extreme heat is not just uncomfortable—it poses a serious threat to cardiovascular health. According to the National Weather Service, extreme heat is the leading weather-related cause of death in the country, surpassing hurricanes and tornadoes in annual fatalities.
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 AHA journal Circulation projects that heat-related cardiovascular deaths could more than double in the coming decades, underscoring the urgent need for public awareness and preventive measures.
“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.”
The physiological response to heat involves sweating to cool the body, leading to fluid loss and dehydration. Simultaneously, the heart must pump more blood to regulate body temperature. These combined demands can overwhelm the cardiovascular system, particularly in individuals with pre-existing heart conditions.
The AHA recommends several steps to protect yourself in extreme heat. Avoid outdoor activity between noon and 3 p.m., when temperatures peak. Dress in lightweight, light-colored clothing, wear a hat and sunglasses, and apply sunscreen. Stay hydrated by drinking water before, during, and after time outdoors, and avoid alcohol and caffeinated drinks that can contribute to dehydration. Take frequent breaks in shade or air-conditioned spaces to allow your body to recover.
Recognizing the warning signs of heat-related illness can save lives. Symptoms of heat exhaustion include headache, cool and pale clammy skin, a fast but weak pulse, dizziness or fainting, weakness or muscle cramps, and nausea or vomiting. If you experience these symptoms, slow down physical activity, move to a cooler place, cool down with cold water, and rehydrate. Medical attention may be necessary. Heat stroke is a medical emergency—call 9-1-1 immediately if you notice a body temperature above 103°F, hot red dry or damp skin, a rapid strong pulse, confusion, headache, loss of consciousness, or nausea.
While physical activity remains essential for heart health, the AHA advises shifting exercise to early morning or evening hours when it’s cooler, or moving workouts indoors to air-conditioned spaces like gyms or community centers. Even activities like walking, swimming, biking, gardening, or walking the dog can be safely enjoyed with proper precautions. For more information on staying heart-healthy in the heat, visit heart.org.
