Intense Weather Events Like Heatwaves, Extreme Cold, and Heavy Rain Increase Heart Disease Risk

Intense weather events like heatwaves, extreme cold, and heavy rain increase heart disease risk in middle-aged and older adults, according to a new study analyzing data from 157 Chinese cities between 2015 and 2020.

The research, published in the American Journal of Preventive Medicine, found that each day with temperatures above 100.4 degrees Fahrenheit raised an individual’s risk of heart disease by approximately 3 percent. Days with heavy rainfall exceeding two inches increased risk by nearly 2 percent, while extreme cold at or below 14 degrees Fahrenheit raised risk by less than 1 percent per day.

Dr. Ya Fang, lead investigator from Xiamen University, explained that the study combined city-level climate data with individual health outcomes to strengthen the link between weather extremes and cardiovascular burden. “By integrating macro (city-level) and micro (individual-level) evidence with advanced spatial and causal analysis methods, we have painted a more complete picture of how climate extremes threaten heart health,” Fang said in a statement accompanying the study’s release.

The findings highlight how environmental factors contribute significantly to cardiovascular disease, which remains a leading cause of death globally. Researchers noted that while the individual risk increase from a single cold day may seem small, repeated exposure over time can accumulate meaningful risk, particularly for older populations.

Western cities in the study showed weaker associations between extreme heat and heart disease compared to eastern cities, suggesting that local factors such as humidity levels, urban design, housing conditions, and heating practices may influence how weather extremes affect heart health. The study did not specify which cities fell into these regional categories.

Heavy precipitation was associated with a consistent increase in heart disease risk across all regions, with each day of more than two inches of rain raising risk by almost 2 percent. Researchers attributed this effect to the physiological strain placed on the cardiovascular system during adverse weather conditions.

The study’s authors emphasized that their results support the need for targeted public health interventions during extreme weather events, especially in regions with aging populations. They noted that China’s rapidly growing elderly demographic — projected to reach 400 million people over 60 by 2035 — increases vulnerability to climate-related health risks.

While the research establishes a clear association between extreme weather and heart disease risk, the authors cautioned that the study design does not prove causation. They called for further research to explore biological mechanisms and to evaluate the effectiveness of adaptive urban planning and clinical interventions in reducing weather-related cardiovascular burden.