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The start of summer means warmer temperatures, spending more time outside, and extended daylight hours to soak up the sun. In the U.S., summer temperatures are on the rise. Climate projections show an increasing number of days above 95 degrees Fahrenheit per year.1
Hot weather can impact heart health, especially for those with cardiovascular disease (CVD). A study from Case Western Reserve University and University Hospitals found rising temperatures could increase heat-related heart disease by 200 percent by 2050.2 Understanding the link between heart problems and heat helps you recognize risks early and take practical steps to keep your heart safe.
Under normal conditions, your body regulates your body temperature when you get too hot. Acting as your body’s thermostat, your hypothalamus sets off an evaporation process when it detects rising heat.3 During the evaporative process, water forms on the surface of skin as sweat, cooling your body as it evaporates.
But extreme or prolonged heat exposures can strain your internal heat regulation mechanism. This puts excess stress on your cardiovascular system as your body attempts to keep you cool.4
The hot weather can pose a spectrum of risk to your heart health. These include:
Dehydration and electrolyte imbalance: When you’re dehydrated, your blood volume drops, forcing your heart to work harder to pump oxygen and nutrients through the body. Moreover, dehydration can affect serum levels for key electrolytes such as sodium, potassium, magnesium, and calcium involved in regulating the heart’s electric signals. Abnormal electrolyte levels can disrupt these signals and your heart’s rhythm.5
Breathing problems: Hot weather can increase ozone pollution, degrading air quality and causing breathing problems. Exposure to polluted air can lead to increased risk of heart attack, stroke, arrhythmia, and worsen heart failure.6
Heat exhaustion: Heat exhaustion occurs when your body overheats and can cause heavy sweating and a weak, rapid pulse. Rest, moving to a cooler place, and drinking water or a sports drink can help alleviate these effects.7
Heat stroke: Heat stroke is the most serious and life-threatening form of heat illness. It can occur if your core body temperature rises to 104 degrees Fahrenheit or higher. Heat stress from heat stroke can put a significant burden on your heart to keep the body cool.7
Some people are more predisposed to health risks in the heat, including those that affect your heart and cardiovascular health. People that should take extra caution in the heat include:
Adults over 65: It's harder for older adults to regulate temperature, which makes them more predisposed to heat-induced illnesses. As you age, you also become more susceptible to heart disease.8 The compounding effects of age and heart disease can increase risk in the summer heat.
Infants and young children: Children have less body mass relative to their size than adults. This makes them less efficient at regulating heat and more vulnerable to heat-induced morbidity and mortality. Staying hydrated, avoiding peak sun hours, wearing appropriate and protective clothing, and using sunscreen can help keep children safe.9
People with cardiovascular disease: Heat stress puts additional demand on your cardiovascular system as your heart works harder to pump excess heat to the skin’s surface.10 Heat can also make you more likely to experience dehydration, blood clots, and electrolyte imbalance, conditions which can lead to other cardiovascular events.6 People with coronary artery disease (CAD), heart failure, arrhythmias, and other forms of CVD should take extra precautions in the heat.
People with chronic conditions: People with chronic conditions, such as hypertension, diabetes, kidney disease, or lung disease, are more susceptible to heat risks. If you have a chronic condition, discuss with your clinician how to plan for the summer heat.
Those affected by situational or environmental factors: Sometimes, your situation or environment can affect your vulnerability to heat illness. People who are dehydrated, lack access to cooling in extreme heat, or work/exercise outdoors face elevated risk.
Hypertension (high blood pressure) is a major risk factor for cardiovascular disease. Heat can either increase or decrease blood pressure based on the variables at play. Blood pressure can change as blood flow increases to the skin, causing your heart to pump harder to keep your body cool.11 When blood is thicker and more difficult to pump, blood pressure can rise.
Heat can also cause vasodilation, the widening of blood vessels. Vasodilation allows more blood to flow through the vessels and can lower your blood pressure.12 Your clinician can advise you how to monitor your blood pressure in the summer heat pressure based on your health status.
A hallmark of summer is spending time in the sun. And it's good for your health, too: sun exposure can help you obtain vitamin D, boost your mood, improve your sleep, and alleviate symptoms of seasonal depression.13 But certain medications used to treat heart conditions can be affected by the heat, such as:
ACE inhibitors and ARBs: Can reduce thirst sensation and affect hydration in the heat.14
Beta blockers: Slows down your heart rate, reducing your body’s cooling mechanism and heat tolerance.15
Calcium channel blockers: Can cause electrolyte shifts and interfere with your body’s ability to regulate temperature.16
Diuretics: Affect dehydration and electrolyte imbalance in the heat.14
Aspirin: Reduces blood vessel dilation near the skin, making it harder for the body to release heat.14
Don’t stop taking medication unless recommended by your clinician. Instead, work with your clinician to understand whether appropriate steps need to be taken in the hot weather.
If you have CVD, take caution in the hot weather, especially when temperatures rise above 90 degrees Fahrenheit. However, your heart health can be impacted by factors outside of temperature, such as the length of heat exposure, overexertion, and your overall health status.17 Recognizing the contributing factors that can induce heat risks can help you protect yourself in extreme temperatures.
No matter your health status, you should plan ahead as summer temperatures rise. If you have heart disease, it's even more pertinent to protect yourself from serious cardiovascular events. Mass General Bringham recommends following these best practices in the heat for heart disease patients:
Avoid alcohol and large meals, which can make it harder for your body to regulate your temperature.
Practice sun safety to prevent sunburn, which can dehydrate you and weaken the body’s internal cooling mechanism.
Increase hydration depending on your health status and recommended intake from your clinician.
Stay in the shade and avoid direct sunlight to keep yourself cool.
Talk to your clinician about your medication and whether changes are necessary for your overall health.
Keeping up with your heart health shouldn’t be a seasonal activity. But summer can serve as a reminder to help you stay ahead of it and protect yourself and your loved ones.
Crimmins AR, Avery CW, Easterling DR, Kunkel KE, Stewart BC, Maycock TK, eds. Fifth National Climate Assessment. U.S. Global Change Research Program; 2023. https://doi.org/10.7930/NCA5.2023
Zamora P. New research connects climate change to increasing heat-related heart disease nationally. Case Western Reserve University Newsroom. https://case.edu/news/new-research-connects-climate-change-increasing-heat-related-heart-disease-nationally. Published May 27, 2026.
Rush University Medical Center. How the Body Regulates Heat. Rush University Medical Center. https://www.rush.edu/news/how-body-regulates-heat.
Harvard Health Publishing Staff. Heat is hard on the heart; simple precautions can ease the strain. Harvard Health Publishing. https://www.health.harvard.edu/blog/heat-is-hard-on-the-heart-simple-precautions-can-ease-the-strain-201107223180. Published November 5, 2019.
Oklahoma Heart Hospital. How Dehydration Can Impact Heart Rhythms. Oklahoma Heart Hospital. https://www.okheart.com/news/how-dehydration-can-impact-heart-rhythms. Published April 27, 2025.
Centers for Disease Control and Prevention. Clinical Overview of Heat and Cardiovascular Disease. CDC. https://www.cdc.gov/heat-health/hcp/clinical-overview/heat-and-people-with-cardiovascular-disease.html. Published September 18, 2025.
Mayo Clinic Staff. Heat exhaustion. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/heat-exhaustion/symptoms-causes/syc-20373250. Updated June 6, 2026.
American Heart Association. How to help prevent heart disease at any age. American Heart Association. https://www.heart.org/en/healthy-living/healthy-lifestyle/how-to-help-prevent-heart-disease-at-any-age. Updated September 23, 2024.
US Environmental Protection Agency. Protecting children and maternal health from extreme heat. EPA. . Updated May 22, 2026.
Cleveland Clinic. How the Heat Can Affect Your Heart. Cleveland Clinic Health Essentials. https://health.clevelandclinic.org/how-the-heat-can-affect-your-heart. Published May 6, 2026.
Mayo Clinic Health System staff. Effects of hot weather, humidity on blood pressure, heart. Mayo Clinic Health System. https://www.mayoclinichealthsystem.org/hometown-health/speaking-of-health/effects-of-high-temperatures-on-blood-pressure-heart. Published June 27, 2023.
Cleveland Clinic. Vasodilation. Cleveland Clinic. https://my.clevelandclinic.org/health/diseases/23352-vasodilation. Updated June 23, 2022.
Cleveland Clinic. The Health Benefits of Sunshine (and How Much You Need Per Day). Cleveland Clinic. https://health.clevelandclinic.org/how-much-sunshine-you-need-daily. Published February 20, 2025.
Centers for Disease Control and Prevention. Heat and Medications – Guidance for Clinicians. CDC. https://www.cdc.gov/heat-health/hcp/clinical-guidance/heat-and-medications-guidance-for-clinicians.html. Published September 18, 2025.
Harvard Health Publishing. Heart problems and the heat: What to know and do. Harvard Health Publishing. https://www.health.harvard.edu/blog/heart-problems-and-the-heat-what-to-know-and-do-202206212765. Published March 12, 2026.
Steiner NS. Some medications can increase risk of heat-related illness. UCLA Health. https://www.uclahealth.org/news/article/some-medications-can-increase-risk-heat-related-illness-2. Published July 24, 2024.
Connolly R. Heart health and summer heat. Mass General Brigham. https://www.massgeneralbrigham.org/en/about/newsroom/articles/heart-health-and-summer-heat. Published July 5, 2024.
