Cold Weather & Heart Health: US Study Links Winter to Higher Cardiovascular Death Rates

After a particularly harsh winter for many across the United States, emerging research underscores a significant, often underestimated threat to public health: cold weather and its impact on cardiovascular health. A novel study, presented at the American College of Cardiology’s Annual Scientific Session (ACC.26) this week, links colder months to a substantial increase in deaths from heart attacks, strokes, and coronary artery disease. Although warmer temperatures also pose a risk, the study reveals the impact of cold is considerably more pronounced.

The Scale of the Problem: 40,000 Excess Deaths Annually

Researchers estimate that cold temperatures contribute to approximately 40,000 additional cardiovascular deaths each year in the U.S., representing about 6.3% of all cardiovascular deaths. Over the two-decade study period (2000-2020), this amounted to roughly 800,000 deaths. In contrast, hot temperatures were associated with around 2,000 extra deaths annually, or about 40,000 over the same timeframe. This research, led by Dr. Pedro Rafael Vieira De Oliveira Salerno of NYC Health + Hospitals/Elmhurst and the Icahn School of Medicine at Mt. Sinai, provides the most comprehensive gaze yet at temperature’s influence on heart-related mortality across a large portion of the U.S. Population. Dr. Salerno will present the study, “County-Level Temperature-Attributable Cardiovascular Disease Mortality in the U.S.,” on Monday, March 30, at ACC.26 in New Orleans.

Previous studies have established a connection between extreme temperatures and cardiovascular deaths, but many were conducted in different countries or focused on limited regions within the United States. For example, a 2024 study published in the Journal of the American College of Cardiology (JACC) demonstrated that exposure to cold temperatures increased the risk of heart attacks. This latest research builds on that foundation, offering a broader, more detailed analysis.

Understanding the U-Shaped Curve of Risk

The research team analyzed monthly temperature data and cardiovascular death rates from 819 locations across the U.S., encompassing approximately 80% of Americans over the age of 25. They identified 23°C (about 74°F) as the temperature associated with the lowest rate of cardiovascular deaths. As temperatures deviated from this point – either increasing or decreasing – death rates rose, following what researchers describe as a lopsided U-shaped curve. This indicates that while both extreme heat and cold elevate the risk of death, the effect of cold is significantly stronger.

Why Does Cold Weather Strain the Heart?

Cold exposure triggers a cascade of physiological responses within the body. These include inflammation and constriction of blood vessels. Blood vessel narrowing can increase blood pressure and reduce oxygen supply to the heart, potentially triggering events like heart attacks or strokes. These changes can significantly increase the likelihood of serious cardiovascular events, particularly for vulnerable populations.

Individuals with pre-existing chronic conditions, such as diabetes, heart failure, and chronic kidney disease, are especially susceptible to the adverse effects of cold weather. As the prevalence of these conditions continues to rise in the U.S., Dr. Salerno notes, we can anticipate a corresponding increase in the number of people vulnerable to temperature extremes.

Beyond Temperature: The Role of Air Quality

While the study focused primarily on temperature, it’s important to consider the interplay with other environmental factors. Cold weather often coincides with increased air pollution from heating sources and stagnant air masses, which can further exacerbate cardiovascular risk. The American Heart Association highlights the combined dangers of cold weather and air pollution, emphasizing the need for comprehensive public health strategies.

Implications for Public Health Planning and Hospital Preparedness

The findings underscore the need for communities to prioritize cold-weather preparedness alongside heat-related mitigation measures when addressing climate-related health risks. “We tend to focus on heat-related impacts of climate change, but climate change also includes extreme cold,” Dr. Salerno explained. “We need to not only have heat-related mitigation measures, but also cold-related mitigation measures.”

The research also has implications for hospital and emergency medical service planning. Anticipating spikes in demand during colder periods can allow healthcare systems to allocate resources more effectively and potentially reduce mortality rates. “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,” Salerno said.

Study Limitations and Future Research Directions

The researchers acknowledge certain limitations of the study. The analysis utilized monthly temperature data, rather than more granular daily measurements. Outcomes were assessed at the population level, rather than tracking individual exposures and health events. Future research will focus on examining the relationship between temperature changes and activations of emergency medical services related to cardiovascular events. The study was published online in the American Journal of Preventive Cardiology concurrent with its presentation at ACC.26.

ACC.26, taking place March 28-30, 2026, in New Orleans, is bringing together cardiologists and cardiovascular specialists from around the world to share the latest discoveries in treatment and prevention. More information about the conference can be found on the ACC website.

What’s next for understanding and mitigating these risks? Ongoing surveillance of cardiovascular events during extreme weather events, coupled with more detailed studies examining individual-level exposures and risk factors, will be crucial. Further research is also needed to identify effective interventions to protect vulnerable populations and improve cardiovascular health during colder months. The ACC is committed to advancing this research and translating findings into actionable strategies for improving patient care.