Tennessee likely has five times more heat-related deaths than counted in official tallies, according to a new investigation from NPR and Boston University.
The institutions created a model to more accurately capture the human toll of heat. In Tennessee, the model estimated that about 125 people died each year from heat exposure between 2018 and 2025.
Heat-related deaths are officially recorded by the Centers for Disease Control and Prevention, which found an average of 25.6 deaths per year during that timeframe in Tennessee. The agency relies on mentions of “heat” in death certificates for its tallies, but heat is not always noted there.
Some communities are developing protocols to better monitor heat-related deaths, but the vast undercount in Tennessee is similar nationwide.
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The analysis estimated about 9,000 annual deaths due to heat in the U.S. between the same time frame of 2018 to 2025, while the CDC average was 1,700 deaths. About a third of those deaths are happening in Florida and Texas alone.
Deaths from heat exposure are expected to climb in the coming years. In recent decades, heatwaves have already become hotter, happened more often and lasted longer — and further climate change will further intensify heat.
Globally, the rate of climate change is still accelerating. Planet-warming pollution from fossil fuel burning reached a record level in 2025. Some nations are plateauing or reducing emissions, thanks to the deployment of renewable energy, while others are still increasing fossil fuel use. The U.S. increased its annual emissions by about 2% last year after decades of slowed pollution, according to an analysis by Rhodium Group, and has plans to expand capacity from methane gas plants by 75% to feed data centers.
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Under a future scenario with high levels of pollution, the research group Climate Central estimated that Nashville could resemble the current climate of Pasadena, Texas, near Houston, by 2060 — signaling that a much greater death toll from heat is possible without significant change.
Tennessee faces another dangerous heatwave this week
Tennessee faces another oven-like heatwave this week.
The National Weather Service forecasted Monday “extreme” heat risks in Nashville and parts of Middle Tennessee.
The heat index will likely exceed 100 degrees across most of the state due to high humidity levels.
The agency has already issued a heat advisory for Memphis and parts of West Tennessee, where heat indices are expected above 105 degrees.
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