Health
Heat linked to an estimated 1,257 deaths in Switzerland this summer
An estimated 1,257 people in Switzerland died from heat between May and August 2026, according to a preliminary report commissioned by the Federal Office of Public Health. The summer was the hottest since records began.
Heat was linked to an estimated 1,257 deaths in Switzerland between May and August 2026, according to a preliminary report by the Swiss Tropical and Public Health Institute, commissioned by the Federal Office of Public Health. The estimate amounts to 5.5% of all deaths during those months, or 14 deaths per 100,000 people.
Switzerland recorded its hottest summer since measurements began, surpassing even 2003. The preliminary toll was substantially higher than in previous years, placing this summer’s heat among the country’s most consequential recorded health events.
The figure is a statistical estimate, not a tally of deaths individually certified as caused by heat. Its 95% confidence interval runs from 1,053 to 1,479 deaths. The estimate covers May through August, and the report’s comparison with 2003 remains provisional because the historical figure includes September.
Trace the Toll Across Temperature Bands
About seven in ten estimated heat-related deaths were associated with hot or very hot days. The preliminary analysis linked 485 deaths to days when the daily mean temperature reached at least 25°C but stayed below 27°C. A further 400 deaths were associated with daily mean temperatures of 27°C or higher.
The remaining estimated deaths were associated with more moderate heat. The figures show that the health burden extended across a range of temperatures, rather than being confined to the hottest days of the summer.
Researchers combined daily mean temperatures recorded by MeteoSwiss with preliminary mortality data from the Federal Statistical Office. Their model accounts for heat’s delayed effects over seven days, linking exposure to deaths that may follow after temperatures rise. These temperature-band totals are part of the preliminary estimate and sit within its confidence interval of 1,053 to 1,479 deaths.
Protect Older People From Indoor Heat
People aged 75 or older accounted for about 85% of the estimated heat-related deaths. The concentration among older people puts care settings and access to cooling in focus as Switzerland assesses the effects of its hottest summer on record.
A study of 615 nursing homes in Ontario, Canada, published in JAMA Internal Medicine, found that extreme heat was associated with an 11% rise in the odds of death in homes without air conditioning. In homes with air conditioning, the increase was 3%. The findings suggest that cooling can help reduce heat-related risks for older residents.
The Ontario results offer evidence about the potential role of indoor cooling, but they are not directly applicable to Switzerland. The Swiss estimate still points to the particular exposure of older people: roughly five out of every six deaths attributed to heat were among those aged 75 and above.
Watch for the Final Figures in 2027
Switzerland’s final 2026 heat-mortality figures are due in spring 2027. The completed analysis will include September, along with breakdowns by age, sex, region and canton, and a comparison with the Federal Statistical Office’s mortality monitoring.
September is excluded from the preliminary estimate because its mortality data were too incomplete. The current analysis therefore covers May to August, while the historical 2003 comparison includes September. Once the final figures are available, that difference in coverage can be addressed in a fuller comparison.
The Federal Statistical Office’s monitoring identifies periods of excess mortality. The Swiss TPH estimate uses temperature data to assess deaths attributable to heat, giving the two analyses different roles in understanding mortality during hot periods. For now, the preliminary estimate places the summer’s toll at 1,257 deaths, with the final assessment set to add the later-month data and detailed breakdowns.