By P Gosselin
A new comprehensive study on the effect of temperature extremes on human mortality shows that cold is far more lethal than heat.
Heat is healthier, researchers find. Symbol image generated by Grok
There’s one conclusion that can be drawn from this: the recent, mostly natural warming is saving lives.
The recent study reported by ScienceDaily article, titled “Cold weather linked to 40,000 extra heart deaths each year in the U.S.,” summarizes a major study presented at the American College of Cardiology’s Annual Scientific Session in March, 2026.
Cold far more dangerous than heat
The study found that cold weather is a much bigger risk to heart health than hot weather. In the United States, cold temperatures are linked to far more cardiovascular deaths than heatwaves are.
Unlike a heatwave, which usually lasts a few days, “moderate cold” can last for many weeks and cause more damage to the body over time.
The researchers say cold weather causes many more heart-related deaths than heat, which is linked to roughly 2,000 extra deaths annually (0.33%). That’s 20 times more! The researchers said approx. 23°C is the safest temperature for heart health.
Cold temperatures cause the blood vessels to narrow (vasoconstriction) and increases inflammation. This can lead to heart attacks, strokes, and coronary artery disease. People with chronic conditions such as diabetes, heart failure, and kidney disease are at the highest risk. While climate change discussions often focus on heatwaves, public health efforts must also focus on the bigger dangers of extreme cold.
The research analyzed data over 20 years of data of 800,000 excess cold-related deaths.
The findings were presented by researchers from the Icahn School of Medicine at Mt. Sinai and are being shared at the American College of Cardiology’s annual scientific session.
Earlier studies reached same results
Mortality risk attributable to high and low ambient temperature: a multicountry observational study
Another large study was conducted by an international team of researchers led by Dr. Antonio Gasparrini from the London School of Hygiene & Tropical Medicine.
The results were published in the prestigious medical journal The Lancet.
The study analyzed more than 74 million deaths across 13 countries (including the US and UK) between 1985 and 2012 and found the following:
- Approximately 7.71% of all deaths were linked to non-optimal temperatures (temperatures that are not ideal for the human body).
- Cold weather was responsible for the vast majority: 7.29% of all deaths. Heat was responsible for only 0.42% of all deaths. This means about 20 times more people are killed by cold than by heat.
Recent global estimates show temperatures cause about 5 million excess deaths each year worldwide, with more than 4.5 million are caused by the cold. Cold weather is much more dangerous to human life than hot weather.
Most people believe that extreme weather (like terrible heatwaves or blizzards) causes the most deaths. But the research found that most “temperature-related” deaths in fact happen on moderately cold days, and not during extreme weather events.
Because cold is more dangerous than heat, some researchers argue that warmer winters will save more lives. They found that in many places, deaths from cold are decreasing faster than deaths from heat are increasing.
The publication in the Journal of the American College of Cardiology JACC, September 2024) examines the relationship between cold weather and the risk of heart attacks
The study analyzed data from over 120,000 heart attack (myocardial infarction or MI) cases in Sweden between 2005 and 2019. The most significant finding is that exposure to cold temperatures or “cold spells” (defined as at least two consecutive days below the 10th percentile for a region) does not cause an immediate spike in heart attacks.
Instead, there is a delayed risk that peaks between 2 and 6 days after the cold exposure. A drop in temperature was significantly associated with an increased risk for all types of heart attacks.
