Extreme Temperatures Linked to Over 69,000 Deaths in the U.S. Over 25 Years

Over the past quarter-century, extreme temperatures have been implicated in more than 69,000 deaths across the United States, with certain populations bearing a disproportionate burden, according to a recent study by Mass General Brigham. Published in the Annals of Internal Medicine on November 17, 2025, the research highlights the pressing need for targeted public health interventions as climate change intensifies.

Analyzing data from the Centers for Disease Control and Prevention's WONDER platform, researchers examined death certificates from 1999 to 2024 that listed temperature exposure as a contributing or underlying cause. They identified 69,256 temperature-related deaths, accounting for approximately one in every 1,000 deaths during this period. Of these, 35% were heat-related, while 65% were attributed to cold exposure.

The study revealed significant demographic disparities in temperature-related mortality. Older adults (aged 65 and above) and males exhibited higher mortality rates compared to their counterparts. Notably, Black individuals experienced the highest heat-related adjusted mortality rates, more than twice those of White individuals. Cold-related adjusted mortality rates were also highest among Black individuals, followed by Whites and Hispanics.

"Our findings show that both heat and cold exposure continue to claim thousands of lives every year in the United States, deaths that are largely preventable," said Dr. Shady Abohashem, the study's senior author and an investigator at the Cardiovascular Imaging Research Center of Massachusetts General Hospital. "While most temperature-related deaths are still driven by cold exposure, heat-related deaths are expected to rise as climate change accelerates."

These findings align with previous research indicating a significant rise in heat-related deaths over recent decades. A 2024 study published in the Journal of the American Medical Association reported a 117% increase in heat-related deaths in the U.S. from 1999 to 2023, with the highest number recorded in 2023. This trend is attributed to escalating climate change, leading to more frequent and intense heatwaves.

The disproportionate impact of temperature-related mortality on vulnerable populations underscores the urgent need for targeted public health interventions. Dr. Abohashem emphasized the necessity for adaptation strategies, stating, "Climate change increases risks of severe weather events, and our findings underscore the need for targeted adaptation strategies, like improving housing quality, access to cooling and heating, and early-warning systems, to protect vulnerable groups as climate extremes intensify."

To mitigate the adverse effects of extreme temperatures, the study advocates for:

• Improving Housing Quality: Ensuring that homes are equipped to handle extreme temperatures through proper insulation and ventilation.

• Enhancing Access to Cooling and Heating: Establishing public cooling centers and providing resources for heating during cold spells.

• Developing Early-Warning Systems: Implementing alert systems to inform communities about impending extreme weather events.

As climate change accelerates, the increasing toll of temperature-related deaths necessitates immediate and targeted public health interventions to protect the most vulnerable populations.