Across the country in June 2025, Americans are experiencing the first heat dome — an extreme, lingering heat wave — of the summer season. This abrupt introduction of unusually hot temperatures has been nothing short of jarring, especially for East Coast dwellers who didn’t have time to properly acclimate.
The summer heat is both relaxing and exhausting. There’s nothing like soaking up the sun while lounging poolside, but there’s also nothing like running errands or exercising outside midday amid peak heat — and not in a positive way.
Heat stress occurs when the body becomes too hot and struggles to cool off. This often happens from prolonged exposure to high temperatures, combined with humidity, physical exertion and dehydration.
Whether you’re doing yard work, working out outside or just walking around in the heat, it’s important for people with heart issues to take extra precautions when spending any time in the hot outdoors.
[Read: Signs of Heat Stroke and Hot Weather Safety Tips]
How Does Extreme Heat Affect the Heart?
First, it helps to understand how heat affects your heart and, subsequently, your entire body.
“When you’re in the heat, your body tries to stay cool by moving more blood to your skin and making you sweat,” says Dr. Sanjay Rajagopalan, a cardiologist and professor of cardiovascular medicine at Case Western Reserve University. “This helps release heat, but it also makes your heart work harder to pump blood.”
— Elevated heart rate. When it’s hot, your heart has to work harder to carry out normal bodily functions and to keep the body cool. As a result, it will beat faster to pump more blood than it normally does compared to when you’re in cooler temperatures, leading to increased cardiovascular strain.
— Dehydration and low blood pressure. Sweating, which the body does to shed heat and regulate temperature, causes fluid and electrolyte loss. If your body loses too much fluid, it can lead to dehydration, which may cause low blood pressure and force the heart to work harder to maintain circulation.
— Hyponatremia or hypernatremia. Extreme dehydration can also lead to an electrolyte imbalance of either low serum sodium levels (hyponatremia) or high serum sodium levels (hypernatremia) in the body. Hyponatremia can cause your heart to mimic heart attack symptoms.
— Acute stress response. The stress heat puts on your body can trigger the release of several stress hormones, including noradrenaline (also known as norepinephrine), which plays a role in the “fight or flight” response. This response can increase your heart rate and blood pressure, which taxes your heart.
[READ: How Climate Change and Extreme Weather Can Hurt Your Health]
Who’s at Risk?
No one is immune to heat stress, but some groups of people may be more at risk than others. These people include:
— People with heart conditions. Those who have preexisting cardiac conditions — such as coronary artery disease, heart failure and arrhythmias — are at elevated risk of heat-related illnesses due to diminished heart function. Common heat-related complications include heat exhaustion and heat stroke, both of which require medical assistance.
— Older adults. Older adults often can’t tolerate heat as well as younger people, as their hearts don’t respond as efficiently to heat stress. Age-related conditions and changes, such as slowed heart rate and mild heart complications, can hinder the body’s ability to stay cool.
— Young children. Young children can overheat more easily than adults, Rajagopalan says. That’s because their bodies aren’t as efficient at getting rid of heat. They may also not recognize symptoms of heat stress.
— People who take certain medications. Certain medications can impair the body’s ability to regulate core temperature, making people more sensitive to heat. For example, diuretics, anticholinergics (medications to treat excessive sweating), beta blockers (blood pressure medications), stimulants and antidepressants can increase a person’s sensitivity to heat and, therefore, increase the risk of heat exhaustion and heat stroke.
[Heart Attack Symptoms in Women: Subtle Signs You Can’t Ignore]
Recognizing Heat Stroke and Heat Exhaustion Symptoms
Common signs of heat exhaustion and heat stroke include:
| Heat Exhaustion | Heat Stroke |
| Usually below 104°F | Above 104° F |
| Normal, though may feel faint | Confusion, agitation, slurred speech |
| Cold, pale and clammy | Hot, red and dry (or damp) |
| Heavy sweating | Sweating may have stopped |
| Fast and weak | Fast and strong |
| Nausea or vomiting | Nausea or vomiting |
| Muscle cramps | No cramps (usually neurological issues) |
| Fainting/dizziness | Possible loss of consciousness/seizures |
5 Essential Tips for Staying Heart-Healthy in a Heat Wave
Spending time in warmer temperatures doesn’t have to be a ticket to heat illness.
“Remember, while your mind may enjoy the heat, your body may not — and your body has to get rid of that heat as fast as it comes in contact with it,” says Dr. Srihari S. Naidu, an interventional cardiologist and professor of medicine at New York Medical College.
Follow these tips to stay safe.
1. Avoid exercising when the heat index is elevated
A more accurate representation of the “real feel” outside is the heat index. Heat index factors in humidity and considers how difficult or easy it may be for your body to cool itself, even in pockets of shade.
In general, the National Weather Service recommends exercising caution when the heat index ranges from 80 to 90 degrees Fahrenheit. As the heat index creeps up to 103 degrees Fahrenheit, that’s when you should really reconsider exerting yourself outdoors.
2. Stay hydrated
In general, you want to aim to drink between 11.5 to 15.5 cups of water daily — no matter the temperature. But when the heat index increases, your fluid intake should too.
You don’t have to just drink water. Other ways to stay hydrated — such as sparkling water, tea and water-rich foods — can help you reach your hydration goals in a healthy manner.
Choosing electrolyte beverages can help maximize your hydration efforts, as electrolytes like sodium help pull water directly into your cells, enabling you to feel hydrated more quickly than just drinking water alone.
3. Dress for the heat
Wearing bright-colored clothing can help reflect heat off of you and prevent you from overheating. Wearing a hat, sunglasses and applying sunscreen are necessary accessories when going out in the heat.
Carrying a portable fan with you or wearing cool packs around your wrists can also help you stay cool when going outside is inevitable.
4. Stay inside during peak sun hours
When you can avoid going outside, especially midday when temperatures often reach their peak, stay indoors with appropriate cooling systems, such as fans and air conditioning. This is especially the case for at-risk individuals.
“Ask your doctor or pharmacist if your medicines increase your risk in the heat,” Rajagopalan advises.
Bottom Line
Warmer temperatures can tax your heart, as it makes it pump blood harder and faster just to sustain your daily activities. But if you take precautions, such as dressing appropriately for the heat and avoiding strenuous workouts in warmer temperatures, you can protect your heart from any heat-related complications. If you or someone you know begins to feel dizzy, overheated, confused or other signs of heat illness, seek immediate medical attention.
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Heart Health and Extreme Heat: 7 Tips to Protect Your Heart During a Heat Wave originally appeared on usnews.com
Update 04/03/26: This story was previously published at an earlier date and has been updated with new information
