Authorities have urged children and older people to stay indoors and issued severe warnings against dehydration and heatstroke.

Meteorologists said temperatures would reach or even exceed 40C from Spain to Switzerland as hot air moves in up from the Sahara due to a storm stalling over the Atlantic and high pressure over central Europe.

The ten-day forecast for Portugal meanwhile says most regions will not exceed highs of 30 degrees Celsius, with parts of the Alentejo being the only exception.