The chill of winter carries a hidden health risk, one that extends far beyond the inconvenience of snow days and icy roads. New research reveals a significant link between cold weather and a surge in cardiovascular deaths across the United States, with an estimated 40,000 additional deaths each year attributed to colder temperatures. This finding, presented at the American College of Cardiology’s Annual Scientific Session, underscores the often-overlooked impact of temperature on heart health and highlights the need for increased public awareness and preventative measures. Understanding this connection – and the factors that make some populations more vulnerable – is crucial as climate patterns continue to shift and extreme weather events grow more frequent.
For years, scientists have suspected a correlation between extreme temperatures and increased cardiovascular events, but pinpointing the extent of the impact across a large and diverse population like the U.S. Has been challenging. Previous studies often focused on specific regions or countries, limiting their broader applicability. This latest research, yet, offers the most comprehensive analysis to date, examining data from 819 locations across the country, representing approximately 80% of Americans over the age of 25. The study builds on prior research published in the Journal of the American College of Cardiology, which demonstrated an increased risk of heart attacks with exposure to cold temperatures.
The U-Shaped Curve of Cardiovascular Risk
Researchers, led by Dr. Pedro Rafael Vieira De Oliveira Salerno, a resident physician at NYC Health + Hospitals/Elmhurst and Icahn School of Medicine at Mt. Sinai, analyzed monthly temperature data and cardiovascular death rates from 2000 to 2020. They identified 23°C (approximately 74°F) as the temperature associated with the lowest rate of cardiovascular deaths. The relationship between temperature and mortality followed a distinct “u-shaped” curve: as temperatures deviated from this optimal point – either increasing or decreasing – the risk of death rose. However, the impact of cold was significantly more pronounced than that of heat.
The data revealed that cold temperatures contributed to roughly 40,000 excess cardiovascular deaths annually, accounting for about 6.3% of all heart-related deaths during the study period, totaling around 800,000 deaths over two decades. In contrast, hot temperatures were linked to approximately 2,000 additional deaths each year (0.33% of all cardiovascular deaths), or about 40,000 over the same timeframe. “Here’s the first time we have actual numbers for most of the United States, and we found the burden of excess deaths associated with cold is quite substantial,” Dr. Salerno explained.
How Cold Weather Impacts the Heart
The physiological effects of cold exposure on the cardiovascular system are complex. Exposure to cold triggers a cascade of responses in the body, including inflammation and constriction of blood vessels. These changes increase the heart’s workload and can elevate blood pressure, potentially leading to serious cardiovascular events like heart attacks and strokes. The narrowing of blood vessels reduces blood flow, increasing the risk of clots and further straining the heart.
Certain populations are particularly vulnerable to these effects. Older adults, individuals with pre-existing chronic conditions such as diabetes, heart failure, and chronic kidney disease, and those with lower socioeconomic status are at heightened risk. “As rates of chronic conditions like diabetes, heart failure and chronic kidney disease rise in the United States, we can expect to see a rise in the number of people who are more vulnerable to the effects of extreme temperatures,” Dr. Salerno noted.
Preparing for a Changing Climate and Protecting Public Health
The findings have significant implications for public health planning and emergency preparedness. The research emphasizes the need to broaden the focus beyond heat-related impacts of climate change to include the dangers of extreme cold. “We tend to focus on heat-related impacts of climate change, but climate change also includes extreme cold. We need to not only have heat-related mitigation measures, but also cold-related mitigation measures,” Dr. Salerno stated.
This includes developing targeted public health campaigns to educate vulnerable populations about the risks of cold weather and providing resources to help them stay safe. Hospitals and emergency medical services should also prepare for potential surges in demand during colder periods. “It’s important for public health planning and also for institutions to anticipate more emergency medical service calls and in-hospital mortality during cold periods. Our systems need to be prepared for that influx of patients,” Dr. Salerno added. Simple measures like ensuring adequate heating in homes, wearing appropriate clothing, and limiting outdoor exposure during extreme cold can significantly reduce risk.
Study Limitations and Future Research
The researchers acknowledge certain limitations to their study. The analysis utilized monthly temperature data, rather than daily measurements, which may have obscured some of the nuances of the relationship between temperature and cardiovascular mortality. The study examined population-level outcomes, rather than individual-level data. Future research will focus on examining how temperature changes correlate with emergency medical service activations related to cardiovascular events, providing a more granular understanding of the impact.
The study, “County-Level Temperature-Attributable Cardiovascular Disease Mortality in the U.S.,” was published online in the American Journal of Preventive Cardiology and presented at the American College of Cardiology’s Annual Scientific Session. Dr. Salerno is scheduled to present the findings on Monday, March 30, at 9:30 a.m. / 14:30 UTC at the Engage Stage for the Young Investigators Award Competition. The ACC.26 conference will be held March 28-30, 2026, in New Orleans.
As communities grapple with the increasing effects of climate change, understanding the full spectrum of temperature-related health risks – including the significant threat posed by cold weather – is paramount. Continued research and proactive public health measures are essential to protect vulnerable populations and mitigate the impact of extreme temperatures on cardiovascular health. The next step in this research will be to analyze emergency medical service data to better understand the immediate impact of temperature fluctuations on cardiovascular events.
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