Summer heatwaves associated with 600 additional deaths in Switzerland

Around 600 more people than normally expected died in Switzerland between June and September as the country experienced its hottest summer since measurements began in 1864.

Federal Statistical Office mortality data, released on Tuesday, showed that the sharpest increase in deaths coincided with the first spell of extreme heat in late June.

Martina Ragettli, an epidemiologist at the Swiss Tropical and Public Health Institute, told Swissinfo that early-season heat can be particularly dangerous because the human body has had less time to acclimatize to high temperatures.

Following cooler conditions in July, another prolonged period of extreme heat struck in early August.

People over 65 accounted for most of the excess mortality, but the data also showed a notable rise in deaths among those under 65 during the second heatwave.

Ragettli said one possible factor was the return to normal working routines after the holiday period, when people working outdoors or spending significant time commuting may have had fewer opportunities to avoid the heat. She stressed, however, that other factors, including the intensity and duration of the heat, could have contributed.

The statistics cannot establish whether heat caused individual deaths, as fatalities may instead be officially attributed to conditions such as heart or circulatory problems.

A more detailed analysis comparing mortality with temperature data is expected in spring 2027.

Currently, eight of Switzerland's 26 cantons have comprehensive plans for responding to extreme heat.