A two-year investigation by NPR and Boston University, published on 31 August 2026, has found that heat-related deaths in the United States are roughly five times higher than official figures, with an estimated 9,000 deaths per year between 2018 and 2025 linked to heat exposure. The official tally, drawn from death certificates and Centres for Disease Control reporting, captures only a fraction of cases where heat acts as a contributing factor rather than the sole cause of death.
The NPR-Boston University analysis concluded that official numbers radically undercount heat deaths, because county-level coroners and medical examiners use inconsistent methods for determining when heat contributed to a fatality. The Associated Press reported separately in August 2023 that this patchwork of county-level counting makes national totals unreliable and widely acknowledged as underreported.
Scientific American noted in September 2023 that official US counts recorded at least 2,300 heat deaths in 2023, but cautioned those figures rely on death certificates that often miss heat’s role entirely. The true toll, according to the NPR investigation, is closer to 9,000 deaths annually, with some years potentially exceeding 10,000, though that upper figure has not been independently verified.
Dr Kristie L. Ebi, a public health expert quoted by the Associated Press, said the undercounting has direct consequences for how governments prepare for extreme heat.
Essentially, all heat related deaths are preventable.
Ebi added that with accurate data, authorities can develop better heat wave early warning systems and target people at higher risk.
Nichole Quick, a health official cited in NPR’s reporting, said the findings confirmed what many in public health had long suspected.
The true impact of this is higher than I think a lot of the numbers show.
The investigation was discussed on WBUR’s Here & Now on 31 August 2026 with Quinn Adams of the Boston University School of Public Health.
The findings carry relevance beyond the United States. South Africa experiences increasingly severe heatwaves, particularly in inland provinces and the Northern Cape, and local health authorities face similar challenges in attributing deaths to heat when multiple underlying conditions are present. Cape Town’s informal settlements, where residents lack insulation and ventilation, are especially vulnerable during summer extremes, yet no systematic heat-mortality tracking system exists at provincial level.
The Western Cape Department of Health has not published heat-attributable mortality data comparable to the US CDC’s reporting. Without such baseline figures, public health planners in South Africa have limited evidence to justify cooling centres, water distribution, or targeted warnings during heatwaves.
What remains unknown is the exact peer-reviewed publication date for the NPR-Boston University analysis, and whether state-by-state undercount multipliers reported by NPR for Michigan, Massachusetts, and Florida will hold up under independent academic scrutiny. Cape Flats News journalist Nadia Davids will check for the peer-reviewed journal publication and any South African heat-mortality studies in the next 14 days.