From hurricanes and wildfires to mudslides and volcanic eruptions, climate change is affecting people everywhere. But it’s not just about natural disasters. Climate change can also bring colder winters and hotter summers. These extreme temperatures can put added pressure on your heart — especially if you have heart disease. But with the right steps, you can protect your heart.

Research on Extreme Weather and Heart Health

A recent study found a link between cold weather and the risk of having a heart attack, also called a myocardial infarction (MI). A heart attack happens when blood flow to part of the heart gets blocked. Without enough blood and oxygen, that part of the heart muscle can become damaged.

Another large study found that spending time in extreme heat and cold can raise the risk of death from cardiovascular conditions (health problems that affect the heart and blood vessels) including heart disease, stroke, and, especially, heart failure.

The Global Burden of Disease (GBD) study, which tracks global health risks, lists extreme temperatures among the top causes of death worldwide. In other words, both heat and cold can seriously affect your heart and overall health.

How Does Cold Weather Affect the Heart?

In cold temperatures, blood vessels narrow to conserve heat. However, this narrowing requires the heart to work harder to pump blood throughout the body, which increases heart rate and blood pressure. This extra demand on the heart can lead to symptoms like chest pain in people with a heart condition.

Here are a few examples of how cold weather can affect the heart:

• Strenuous activity — Taking on a strenuous activity, like shoveling snow, puts more stress on the heart. In fact, research from the American Heart Association (AHA) shows that the exertion of shoveling snow may lead to an increased risk of a heart attack or even sudden cardiac arrest (when the heart suddenly stops beating).
• Chest pain — Cold weather may cause people with coronary artery disease (CAD) to experience angina pectoris, or chest pain and discomfort. CAD is the most common cardiovascular disease in the United States. It’s a type of blood vessel disease that develops when plaque builds up in the coronary arteries.
• Accidental hypothermia — Another potential danger is accidental hypothermia, which develops when your body temperature falls below roughly 95 degrees Fahrenheit, and your body can’t make enough heat to stay warm.

Accidental hypothermia can damage your heart and is life-threatening. Its symptoms include:

• Lack of coordination
• Mental confusion
• Shivering
• Sleepiness
• Slowed reactions

Most often, the very young and the very old are most at risk of accidental hypothermia. That’s usually because they may have trouble moving around, dressing warmly, or getting to a safe place. They might also have a hard time telling someone when they’re cold or asking for help.

How Does Hot Weather Affect the Heart?

Just like cold weather, hot weather makes the heart work harder to keep the body’s core temperature at normal levels. On a very hot and humid day, the heart can circulate two to four times as much blood each minute compared with a cool day.

This extra demand is especially dangerous if you already have heart disease. The Environmental Protection Agency (EPA) says that high heat combined with heart problems causes about one in four heat-related deaths.

In addition, certain heart medications — like beta-blockers, angiotensin-converting enzyme inhibitors, and diuretics, which decrease sodium levels — can interfere with the body’s natural response to heat, such as sweating and increased blood flow to the skin.

Let’s take a closer look at how hot weather can put additional strain on your heart.

Heart Arrhythmias

Research from the AHA suggests that extreme heat may double or triple the risk of arrhythmia (irregular heart rhythms) in people with implanted defibrillators (a device used to treat arrhythmia). The findings showed that outdoor temperatures that reach 100 F or higher nearly tripled the number of episodes of atrial fibrillation, or AFib (a type of arrhythmia), in people with implanted electronic devices.

Heart Failure

Heart failure occurs when the heart does not pump blood as well as it should. This leads to a backup of blood flow and a buildup of fluid in the lungs, which can cause trouble breathing.

Extreme heat can worsen the effects of heart failure because it forces the heart muscle to work harder to cool the body. This added strain can make symptoms like shortness of breath, fatigue, and swelling even worse.

Protect Your Heart in Extreme Weather

It’s important to know how to protect yourself in extreme heat or cold, especially if you have a preexisting heart condition. Below are tips for staying safe in the winter and the summer.

Heart-Healthy Tips in Cold Weather

The AHA shares tips on how to keep warm and protect your heart in cold weather:

• Focus on your hands and feet, which tend to lose heat quickly.
• Wear a scarf and hat, which can prevent heat loss.
• Wear layers, which can provide insulation from the cold.

The AHA also gives some practical pointers to follow when participating in strenuous activities like shoveling snow during the winter months, such as:

• Avoid alcohol before and immediately after shoveling. It can cause you to overestimate your perception of warmth and underestimate your perception of strain on the body.
• Know the warning signs of a heart attack and listen to your body.
• Learn CPR so you can act quickly if you see someone collapse. Hands-Only CPR can double or triple a victim’s chance of survival.
• Take frequent breaks.
• Talk to your doctor if you have any health concerns.

You may want to wear a heart disease medical ID bracelet if you have cardiovascular disease. That way, you’re prepared for a medical emergency like a heart attack or stroke.

Heart-Healthy Tips in Hot Weather

The British Heart Foundation shares these tips for protecting your heart in hot weather:

• Avoid alcohol because it can lead to dehydration.
• Avoid vigorous outdoor exercise.
• Choose cold foods, like salads and fruit.
• Drink plenty of fluids to help make up for the water your body is losing through sweat.
• Wear light, loose-fitting clothes.

Talk to Your Doctor

If you have heart disease, ask your doctor how to stay safe during extreme weather. They can help you understand your risk and give advice on what to do in cold or hot conditions. They may also adjust your medications or recommend other steps to protect your heart. Staying informed — and planning ahead — can help you protect your heart, no matter what the forecast holds.

Find Your Team

MyHeartDiseaseTeam is the social network for people with heart disease and their loved ones. On MyHeartDiseaseTeam, more than 62,000 members come together to ask questions, give advice, and share their stories with others who understand life with heart disease.

Have you noticed changes in your heart symptoms during very hot or cold weather? What steps do you take to protect your heart when the weather turns extreme? Share your experience in the comments below or start a conversation by posting on your Activities page.