A marine heat wave in the Mediterranean is combining with a powerful heat dome to cause Europe to swelter under a brutal early summer heat wave.

Barcelona recorded its hottest month of June since records started over a century ago, Spain's national weather service said on Tuesday as Europe remained in the grip of the first major heat wave this summer.

France and the rest of Europe are still in the grips of the first major heat wave this summer even as conditions began to improve in some parts of the region