A thermometer displays a temperature approaching 40 degrees Celsius during a period of extreme heat in Propriano, South Corsica, France on June 22, 2026. —Grichka Beysson-Leandri—Hans Lucas/AFP/Getty ImagesEurope is heading into its second deadly heatwave in two months after several countries experienced a “heat dome” last month with record-breaking temperatures that killed several people across the continent.Forecasters have warned that tempera…