Following one of the coldest winters in recent memory across large parts of the country, new research is drawing attention to a frequently underestimated consequence of low temperatures: a marked rise in cardiovascular deaths. Months characterised by colder weather are associated with significantly higher rates of fatalities from heart attacks, strokes and coronary artery disease compared with milder periods. The study, presented at the American College of Cardiology’s Annual Scientific Session (ACC.26), also found that higher temperatures correspond with increased cardiovascular deaths. However, the effect is considerably less pronounced than that observed in colder conditions.
While earlier studies have established links between extreme temperatures and cardiovascular mortality, much of that research has either focused on populations outside the United States or examined only limited regions within it. For instance, prior work published in the Journal of the American College of Cardiology highlighted an elevated risk of heart attacks during cold weather exposure. The latest study expands on this by offering a far more comprehensive analysis, covering a wide geographic and demographic range across the United States, thereby providing a clearer picture of how temperature variations influence cardiovascular outcomes at scale.
According to the study’s lead author, Pedro Rafael Vieira De Oliveira Salerno, a resident physician at NYC Health + Hospitals/Elmhurst and the Icahn School of Medicine at Mount Sinai, the findings represent a significant advancement in understanding the national burden of temperature-related deaths. For the first time, researchers have been able to quantify the impact of cold weather across most of the United States, revealing that the number of excess deaths linked to lower temperatures is substantial and cannot be overlooked in public health discussions.
The research team analysed monthly temperature data alongside total cardiovascular deaths across 819 locations, representing approximately 80% of the U.S. population aged over 25. Spanning the years 2000 to 2020, the analysis identified an optimal temperature—around 23°C—at which cardiovascular death rates were lowest. Mortality rates increased progressively as temperatures moved either below or above this benchmark, illustrating a clear relationship between environmental conditions and cardiovascular risk.
The pattern observed followed an uneven U-shaped curve, with both extreme cold and extreme heat contributing to higher mortality. However, the increase in deaths was significantly steeper during colder periods. Researchers estimated that cold weather was responsible for approximately 40,000 excess cardiovascular deaths annually, accounting for about 6.3% of such deaths, and totalling around 800,000 over two decades. In contrast, heat-related excess deaths were far fewer, estimated at 2,000 per year, or 40,000 over the same period. Physiologically, cold exposure can trigger inflammatory responses and cause blood vessels to constrict, increasing the likelihood of serious cardiovascular events, particularly among older adults and individuals with chronic conditions.
The findings carry important implications for public health planning, especially in the context of climate change. As chronic illnesses such as diabetes, heart failure and kidney disease become more prevalent, a growing segment of the population may be increasingly vulnerable to temperature extremes. While much attention has been directed towards the dangers of rising heat, the study underscores the need also to address the risks posed by cold weather. Health systems and communities must prepare for seasonal surges in emergency calls and hospital admissions during cold spells, ensuring adequate resources and preventative strategies are in place. Although the study relied on monthly data and population-level analysis, future research aims to examine more granular, real-time associations, including the relationship between temperature fluctuations and emergency medical service activations.
More information: Pedro Rafael Vieira de Oliveira Salerno et al, Cardiovascular disease mortality attributable to monthly non-optimal temperature in the united states: a county-level analysis, American Journal of Preventive Cardiology. DOI: 10.1016/j.ajpc.2026.101514
Journal information: American Journal of Preventive Cardiology Provided by American College of Cardiology
