An aerial view shows people relaxing on a floating platform at Silbersee lake on a hot summer day in Haltern, Germany, July 4, 2015. A widespread, long-lasting heatwave will affect much of France, Britain, Belgium, the Netherlands and western Germany. REUTERS/Ina Fassbender 

A man takes a shower during the second heat wave of the summer on Sacaba beach in Malaga, southern Spain, July 5, 2015. As Germany and Spain sweated and London sweltered through its hottest July day on record this week, scientists said it is "virtually certain" that climate change is increasing the likelihood of such heat waves in Europe. Temperatures will rise up to 44 degrees Celsius (111.2 fahrenheit) in some parts of Spain and will continue during a week, the Spanish Agency of Meteorology (AEMET) said on Thursday. REUTERS/Jon Nazca 

Children jump from a 3 meters platform into the water on a hot summer day in the western Austrian city of Hall in Tirol, July 5, 2015. REUTERS/Dominic Ebenbichler 

Women cool off at a swimming pool during the second heat wave of the summer, in Ronda, southern Spain, July 5, 2015. As Germany and Spain sweated and London sweltered through its hottest July day on record this week, scientists said it is "virtually certain" that climate change is increasing the likelihood of such heat waves in Europe. Temperatures will rise up to 44 degrees Celsius (111.2 fahrenheit) in some parts of Spain and will continue during a week, the Spanish Agency of Meteorology (AEMET) said on Thursday. REUTERS/Jon Nazca 

An aerial view shows people at a beach on the shores of the Silbersee lake on a hot summer day in Haltern, Germany, July 4, 2015. A widespread, long-lasting heatwave will affect much of France, Britain, Belgium, the Netherlands and western Germany. REUTERS/Ina Fassbender 

People refresh themselves with an atomizer in an artificial beach during a heat wave in Brussels, Belgium, July 4, 2015. Temperatures in Belgium are expected to reach 36 degrees Celsius, according to weather forecaster from the Belgian Royal Institute of Meteorology. REUTERS/Eric Vidal 

A man takes a sunbath at an artificial beach during a heat wave in Brussels, Belgium, July 4, 2015. Temperatures in Belgium are expected to reach 36 degrees Celsius, according to weather forecaster from the Belgian Royal Institute of Meteorology. REUTERS/Eric Vidal 

People take part in a giant water fight on a hot summer day in central Brussels, Belgium, July 3, 2015. A widespread, long-lasting heatwave will affect much of France, Britain, Belgium, the Netherlands and western Germany. According to forecast, the temperature for Friday could reach 35 degrees Celsius (95 degrees Fahrenheit). REUTERS/Yves Herman 

Three men relax as they float in their dinghies during hot temperatures down the Sihl river in Zurich July 3, 2015. REUTERS/Arnd Wiegmann 

Residents at the Ter Biest house for elderly persons refresh their feet in a swimming pool on a hot summer day in Grimbergen, Belgium, July 2, 2015. The United Nations warned on Wednesday of the dangers posed by hot weather, especially to children and the elderly, as much of Europe sweltered in a heatwave whose intensity it blamed on climate change. REUTERS/Yves Herman 

People enjoy the warm sunny weather in the futuristically designed 'Badeschiff' (Pool ship) on the Spree river in Berlin, Germany, July 2, 2015. REUTERS/Fabrizio Bensch 

A woman fans herself while waiting for a train on the London underground on a hot day in London, July 1, 2015. Temperatures in London hit 34.5 degree Celsius (94 degree Fahrenheit) by lunchtime, making it the hottest day in July in nine years in Britain. REUTERS/Paul Hackett 

People stand on water slide platform at 'Grugabad' open-air swimming pool on a hot summer day in Essen, Germany, June 30, 2015. A widespread, long-lasting heat wave will spread across much of France, U.K., Belgium, the Netherlands and western Germany with forecast highs on Wednesday reaching 35 degrees Celsius (95 degrees Fahrenheit). REUTERS/Ina Fassbender 

Aiden (L) and Ty Johnston play under a fountain in Nottingham, Britain June 30, 2015. Britain's Meteorological Office has warned of the possibility of heatwave conditions, with temperatures reaching their highest of the year on Tuesday and Wednesday. REUTERS/Darren Staples 

Children collect water at a public fountain at the Louvois square on a hot summer day in central Paris, France, July 1, 2015. A widespread, long-lasting heat wave will spread across much of France, U.K., Belgium, the Netherlands and western Germany with forecast highs on Wednesday reaching 35 degrees Celsius (95 degrees Fahrenheit). REUTERS/Charles Platiau 

Lifeguards Chris Payne (L) and Nina Bassam keep watch on a hot Summer day at Brighton beach in Britain June 30, 2015. Britain's Meteorological Office has warned of the possibility of heatwave conditions, with temperatures reaching their highest of the year on Tuesday and Wednesday. REUTERS/Luke Macgregor 

Sun hats are seen for sale in converted telephone boxes on a hot Summer day at Brighton beach in Britain June 30, 2015. Britain's Meteorological Office has warned of the possibility of heatwave conditions, with temperatures reaching their highest of the year on Tuesday and Wednesday. REUTERS/Luke MacGregor

Hadley Eames covers Gemma Cousins with stones as they sunbathe on a hot Summer day at Brighton beach in Britain June 30, 2015. Britain's Meteorological Office has warned of the possibility of heatwave conditions, with temperatures reaching their highest of the year on Tuesday and Wednesday. REUTERS/Luke MacGregor

An aerial view shows people relaxing on a beach on the shores of the Silbersee lake on a hot summer day in Haltern, Germany, July 1, 2015. A widespread, long-lasting heatwave will affect much of France, Britain, Belgium, the Netherlands and western Germany. Forecast highs on Wednesday could reach 35 degrees Celsius (95 degrees Fahrenheit). REUTERS/Ina Fassbender 

Australian singer and musician Lija Rolavs who performs as Princess Freesia is caught by a wave on a hot Summer day at Brighton beach in Britain June 30, 2015. Britain's Meteorological Office has warned of the possibility of heatwave conditions, with temperatures reaching their highest of the year on Tuesday and Wednesday. REUTERS/Luke MacGregor