Cold weather may pose a greater threat to heart health than many people realize.
A new study suggests that lower temperatures are linked to a significant increase in deaths from heart attacks, strokes, and other cardiovascular diseases across the United States.
The research, presented at the American College of Cardiology’s Annual Scientific Session and published in the American Journal of Preventive Cardiology, provides one of the most comprehensive analyses of how temperature affects heart-related deaths in the U.S.
Researchers examined data from 819 locations across the country, covering about 80% of the U.S. population over the age of 25. They analyzed monthly temperatures and cardiovascular death rates over a 20-year period from 2000 to 2020.
The findings showed a clear pattern. The lowest rates of cardiovascular deaths occurred at around 23°C (74°F). As temperatures moved either below or above this level, death rates increased. However, the increase was much sharper during colder weather than during hotter conditions.
In fact, the researchers found that cold temperatures were associated with about 40,000 additional cardiovascular deaths each year. Over two decades, this adds up to around 800,000 deaths. By comparison, hot weather was linked to about 2,000 extra deaths annually, or roughly 40,000 over the same period.
This pattern forms what scientists describe as a “U-shaped curve,” where both cold and heat raise risks, but cold has a much stronger impact.
There are several reasons why cold weather can be harmful to the heart. When the body is exposed to low temperatures, blood vessels tend to narrow, which increases blood pressure and makes the heart work harder. Cold conditions can also trigger inflammation and other stress responses in the body, raising the risk of heart attacks and strokes.
Certain groups are especially vulnerable. Older adults and people with chronic health conditions, such as diabetes, heart failure, or kidney disease, are more likely to be affected by temperature extremes.
The researchers say their findings highlight an important issue in public health planning. While much attention is given to the dangers of heat waves, especially in the context of climate change, the risks associated with cold weather are often overlooked.
They suggest that communities and health systems should prepare not only for heat-related health problems but also for increased demand during cold periods. Hospitals and emergency services may see more patients during colder months, and planning ahead could help save lives.
The study does have some limitations. It relied on monthly temperature data rather than daily changes, and it looked at overall population trends rather than individual cases. Even so, the large scale of the data provides strong evidence of a link between temperature and heart health.
In simple terms, while both heat and cold can affect the heart, cold weather appears to be far more dangerous. Staying warm and protecting vulnerable individuals during colder months could be an important step in reducing preventable deaths.
If you care about heart health, please read studies about the best time to take vitamins to prevent heart disease, and scientists find how COVID-19 damages the heart.
For more health information, please see recent studies about Aspirin linked to higher risk of heart failure, and results showing Blackcurrants could improve artery functions, blood pressure in older people.
