Swiss heat deaths in summer 2026 estimated at about 1,260, up from earlier 600

Summer toll estimate

The Swiss Tropical and Public Health Institute (Swiss TPH) estimates that heat caused 1,257 deaths in Switzerland between early May and the end of August 2026. The figure comes from a provisional analysis made for the Federal Office of Public Health (FOPH), and it equals 5.5% of all deaths registered in those four months, or about 14 deaths per 100,000 residents. Watson and NZZ round the number to about 1,260, while the Le Temps headline gives 1,247 even though its body text uses 1,257. The estimate leaves out September, which was also abnormally hot. The Federal Council had already said in September that excess mortality of about 570 people over 65 was expected.

Who was affected

Older people bore most of the burden. About 85% of the estimated heat deaths were people aged 75 or older, according to the Swiss TPH figures reported by Le Temps and Watson. Roughly seven in ten deaths were attributed to days with a daily mean temperature of at least 25 degrees. Watson gives the split as 485 deaths on hot days of 25 to 27 degrees and 400 on very hot days above 27 degrees. Those thresholds match the level three and level four heat warnings set by MeteoSwiss, and Le Temps reports that the institute describes heat as the deadliest natural hazard in Switzerland.

Hot days, 25 to 27 degrees485

Very hot days, above 27 degrees400

Hot days, 25 to 27 degrees

485 deaths

Very hot days, above 27 degrees

400 deaths

Data from the article text

Why the estimate rose

The earlier figure of about 600 came from an excess-mortality calculation, which compares deaths in a summer with those in comparable months of earlier years. NZZ reports that this method missed heat deaths hidden under other causes such as cancer. The new approach estimates, month by month, the share of deaths that heat can be blamed for, using death rates and temperatures. Martina Ragettli, research group leader for climate and health at Swiss TPH, says the 2003 heatwave found Switzerland less ready than it is now.

“In 2003 the heatwave hit the country still relatively unprepared.”

She credits cantonal heat action plans and greater public awareness for part of the difference, arguing that without those measures this year's toll would have been higher still.

“I assume that without such measures we would have had even more heat deaths this year.”

Comparison with 2003

NZZ reports that the new figures show no more heat deaths than in the summer of 2003, even though temperatures in central Europe were higher this time. Watson describes the estimate as being of a similar order of magnitude to 2003, but says a direct comparison is not yet possible. The 2026 analysis covers only May to August, whereas the historical reference values run to the end of September. NZZ also says the summer toll was clearly higher than assumed before.

Earlier estimate (about)600

Swiss TPH provisional estimate1,257

Earlier estimate (about)

600 deaths

Swiss TPH provisional estimate

1257 deaths

Data from the article text

Next steps

Final figures are due in spring 2027, when September will be included along with breakdowns by age group, sex, large region and canton. Le Temps says Swiss TPH will publish a more precise study in the spring. The estimate rests on measured daily mean temperatures from MeteoSwiss and provisional death data from the Federal Statistical Office. The timeline below shows the main steps so far.