Heatwave warning extended as temperatures in Switzerland could hit 40C

Summer has arrived in Switzerland in full force, as temperatures over the weekend soared well into the mid-thirties. The federal government has now extended level 3 and 4 heat warnings until at least Saturday, June 27.

Swiss government extends heatwave warning

It’s going to be another sweltering week across the country as Switzerland’s first heatwave of 2026 continues. A level 3 heat warning has been in place since Thursday, June 18, when temperatures began to rise across several Swiss cities, and has since been extended until at least Saturday. A level 4 danger warning, the second-highest, also currently applies to northern parts of Switzerland including Basel.

Monday, Tuesday and Wednesday will continue to see sunny and clear days with highs of 35 degrees in some cities. There may be the chance of an occasional thunderstorm, with humidity levels sitting between 30 and 50 percent throughout the day. Evening temperatures will only bring slight relief to the heat, dropping to around 18 to 20 degrees.

Level 4 heat warning may be extended

The heatwave is expected to “last until at least next weekend”, as temperatures are expected to peak later in the week, according to a MeteoSwiss blog. So much so that the level 4 danger warning “may be extended to a larger area”. 

Weather forecasters predict that by Friday, temperatures may reach 36 degrees in Geneva, 37 degrees in Basel and could even hit 40 degrees in some places, according to Nau. Thunderstorms and clouds are also looking more likely towards the end of the week.

June records broken in Buchs and Delémont

The recent hot weather is caused by a “large high-pressure system over Central and Southern Europe”, which has brought “subtropical air masses” and caused particularly high temperatures across much of Switzerland, according to MeteoSwiss. 

Record temperatures have already been beaten in some cities. In Buchs, Aargau, it was a scorching 36,1 degrees on Sunday, beating the previous June record of 35,9 degrees, reports Watson. Similarly, in Delémont, Jura, a new June record of 35,4 degrees was set, passing the previous temperature record of 35.