Measurements are taken of the Kebnekaise mountain glacier which is melting at an unprecedented rate

Arctic reindeer sought shade in road tunnels, Sweden’s biggest glacier melted and France faced a snail shortage as Europe prepared for the hottest day since records began.

Tourists and locals have been told to drink water, stay out of the sun and avoid unnecessary effort. Spain and Portugal could register their highest ever temperatures in the next few days and might break Europe’s record of 48C set in Athens in 1977.

In southeast Spain a 42-year-old rail worker died from a heart attack after working in temperatures of up to 36C. Health officials urged people to wear light clothes made from natural fabrics, to eat light meals and to keep their houses as cool as possible.

In France, where temperatures are likely to rise above