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.

Europe sizzled in its first major heat wave of the summer on Tuesday. Barcelona recorded its hottest June in over a century.

The heat wave that has blanketed much of Europe is expected to linger over the continent this week, driving up temperatures and offering little reprieve.

Several European regions had their highest temperatures on the last day of June, as a heatwave continues into July.

The heat was so expansive that mountaintops, including the French Alps, that are usually frozen from snowpack saw record temperatures. Heat records were set for June in Spain and Portugal.

Four people died in Spain, two in France and two in Italy as an early summer heatwave continued to grip much of Europe on Wednesday, triggering health alerts and forest fires and forcing the closure of a nuclear reactor at a Swiss power plant.

Spain, France, Portugal, Greece and Italy experienced severe conditions over the weekend. The heat wave is expected to persist into the middle of the week.

Spanish authorities say two people have died in northeastern Spain in a wildfire that spread quickly before firefighters brought it under control. Catalan regional president Salvador Illa