Pygmy hippo cools off at London Zoo

The alert is the first issued by the Met Office since the national meteorological service launched its extreme heat national severe weather warning system at the start of June to help better inform people of the risks hot weather can bring.

Much of Britain has seen heatwave conditions in recent days but temperatures are expected to rise further, possibly reaching 33 degrees Celsius in some western parts of the country, the Met Office said.

A record-breaking heatwave this month killed hundreds of people in Canada and the United States. Europe also has been unusually hot and flooding has devastated parts of Germany, Belgium and other countries.