The United Nations' World Meteorological Organization has warned that extreme heat waves in Europe will become more frequent due to climate change after high temperatures scorched western parts of the continent.

Thousands of people were forced to evacuate areas of France and Spain as tinder-dry forests burned, and the United Kingdom baked during its hottest day on record, which caused wildfires to rip through homes and businesses.

"In the future, these kinds of heat waves are going to be normal, and we will see even stronger extremes," WMO Secretary-General Peterri Taalas said at a news conference.

Euronews reported that Germany had seen its hottest day of the year so far with several cities recording temperatures over 40 C.

The heat wave continued to engulf the continent on Wednesday, with Belgium and parts of Germany forecast to experience even higher temperatures.

In Maastricht, the Netherlands, the thermometer reached 38.9 C on Tuesday with that number expected to be surpassed on Wednesday.

More than 748 heat-related deaths have been recorded in Spain and Portugal, and Spanish Prime Minister Pedro Sanchez has blamed deadly forest fires on global warming, the AP reported.

Record highs were recorded in many areas of France, and the southwest of the country has experienced its biggest wildfires in more than 30 years, Agence France-Presse reported. Fires in the last seven days have overwhelmed vast areas of the Gironde region, where nearly 37,000 residents were forced to evacuate.

The BBC reported that temperatures exceeded 40 C in several locations in the United Kingdom for the first time ever on Tuesday, with a new high mark of 40.3 C set in Coningsby, in Lincolnshire, beating the previous record of 38.7 C in Cambridge, set in 2019.

The London Fire Brigade said there had been "a huge surge" in fires across the capital, with some residents evacuated from their homes as wildfires broke out due to the intense heat, Sky News reported.