LONDON, July 2 (Reuters) - 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.

Europe is sweltering under an intense heatwave, as temperatures soar across Spain, Portugal, France and Italy for one of the hottest summer starts ever recorded.

Barcelona has recorded its hottest month of June since records started over a century ago, Spain’s national weather service said. The Can Fabra Observatory, located on a hill overlooking Barcelona, reported an average temperature of 26 degrees Celsius (78 degrees Fahrenheit),

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.