How Sudden Temperature Changes Affect Your Heart

July 06, 2026

Woman in winter clothes beside construction worker wiping sweat from forehead

Unpredictable weather in many parts of the U.S. often brings big swings in temperature, especially when the seasons change. But for some people, including older adults and people with heart disease, these sudden changes in temperature can be dangerous.

Why Is Body Temperature Regulation Important?

Your body needs to keep a steady internal temperature to work properly. This is called your core temperature, and it typically stays around 98.6°F. The body controls temperature through a process called thermoregulation.

“When thermoregulation fails, a person’s core temperature can climb too high (hyperthermia) or drop too low (hypothermia),” says Haitham Khraishah, MD, a preventive cardiologist at University Hospitals Harrington Heart & Vascular Institute. “Both conditions are medical emergencies that can lead to vital organ failure and even death if not treated.”

The Role of Circulation

One way the body regulates its core temperature is through the circulatory system. When it’s hot outside, the blood vessels in your skin widen. This is called vasodilation. It moves warm blood from your core to your skin, where heat can escape into the air. This helps protect your vital organs and keeps your core temperature steady.

“Vasodilation and sweating work together to cool you down,” says Dr. Khraishah. “Blood vessels widen to bring warm blood to the skin, and sweat helps release that heat.”

The opposite happens when the air gets chilly. Blood vessels near your skin get smaller. This process – called vasoconstriction – reduces blood flow to the skin so your body doesn’t lose heat. Warm blood stays around important organs like your heart, lungs, and brain instead.

Sharp Drops and Rises in Temperature

Most younger and healthy people adjust to temperature changes without problems. But sudden shifts can put stress on the heart and blood vessels in older adults and people with heart disease. This can affect blood pressure and heart rate.

That’s why hospitals often see more heart-related problems during extreme weather. These problems include:

“Heat waves can cause dehydration, lower blood pressure and increased heart rate,” says Dr. Khraishah. “This makes the heart work harder, especially in older adults or people with heart disease.”

Dr. Khraishah also notes that humidity can make things worse. When the air is humid, sweat does not evaporate well. That makes it harder for the body to cool down.

“Cold weather can also be dangerous,” Dr. Khraishah says. “It raises blood pressure and makes the heart work harder. In people with heart problems, this increases the risk of heart attack and stroke.”

Signs Your Body May Be Struggling to Adjust to the Temperature

Watch for these warning signs that your body is having trouble adjusting to temperature changes:

Dizziness
Lightheadedness
Chest pain
Shortness of breath
Palpitations
Fainting
Confusion
Severe fatigue
Worsening swelling

“Sudden exposure to extreme heat can also cause people to experience heavy sweating, dehydration, nausea or muscle cramps,” says Dr. Khraishah. “Extreme cold can cause excessive shivering, numbness, slowed thinking and trouble speaking. These symptoms should not be ignored, especially in people with heart disease or other chronic medical conditions.”

How to Protect Your Heart From Dramatic Swings in Temperature

Be mindful of weather and temperature forecasts, particularly if you have heart disease, high blood pressure or circulation problems. Some other helpful tips:

When possible, give your body time to adjust when moving between noticeably colder and warmer places.
Dress in layers so you can add or remove clothing as needed.
Stay well hydrated: Without enough water, your body cannot produce the sweat needed to help cool off.
Avoid intense outdoor activity when temperatures are extreme.