Heat is killing far more people than official statistics show — in the US and Europe
A new NPR and Boston University investigation finds that heat kills five times more Americans each year than official records show, while in Europe this summer's heatwaves have already caused over 32,000 excess deaths.
The US: heat kills far more than official numbers show
27-year-old Adam Willson lived with his mother Debbie in sun-scorched Tucson, Arizona. Both had DiGeorge syndrome, a genetic disorder that made them highly sensitive to heat and caused heart problems. In June 2024, when temperatures topped 100°F almost every day, their swamp cooler broke and the family couldn't afford to fix it. One morning Debbie found her son dead in bed. His death certificate lists only "unknown natural causes" — heat isn't mentioned, though his mother and the responding emergency team believed it was the main cause.
As NPR reports, this case illustrates a wider problem: official records show heat killed an average of about 1,700 Americans a year between 2018 and 2025, but a new investigation by NPR and Boston University estimates the real toll at roughly 9,000 a year — five times higher. Epidemiologist Quinn Adams explains that heat is rarely a death's sole cause; it worsens existing conditions, but doctors often don't document it without clear proof. In Tucson, which once saw fewer than one day a year above 110°F, the city now averages nine such days, reaching as high as 18 in a single year.
Europe: over 32,000 excess deaths already this summer
Europe's heatwaves have also taken a heavy toll this summer. According to EuroMomo, the European mortality monitoring platform, roughly 32,000 excess deaths were recorded across 23 countries over two months. A partial AFP tally, based only on national reports from eight countries (Germany, France, Belgium, Spain, England, the Netherlands, Austria and Portugal), already puts the figure above 33,000 — both sources suggest the final total is likely to be even higher.
Researchers stress that mortality risk rises sharply from age 45, and that people aged 15 to 64 are not spared either. In France, the June–July heatwave caused an estimated 5,764 excess deaths; while two-thirds affected people over 75, the increase was already visible from age 45. Inserm researcher Basile Chaix notes that mortality among working-age adults rose as much as it did among 65-to-84-year-olds. Heat, he says, acts as a "cofactor" that worsens pre-existing risks — accidents at work and on the road, alcohol consumption, violence and suicide. In France alone, 301 people drowned between June and August — 14% more than the previous year.
What experts recommend
Experts on both sides of the Atlantic call for better tracking of heat's role in deaths, clear rules for halting outdoor and workplace activity during extreme heat, and access to cool spaces for both workers and the public.
