A group of people take refuge from the heatwave with a hose-pipe shower in their garden pond, Streatham, London. (Photo by Fox Photos/Getty Images). 1933

New York children splash about in a flooded street after the police opened the fire hydrants to beat the unbearable heat of summer. (Photo by Keystone/Getty Images). 1957

A group of children having a hose-down from firemen during a heatwave in London. (Photo by Hulton Archive/Getty Images). 1935

A boy having a cool shower during a heat wave in Britain. (Photo by Fox Photos/Getty Images). 1956

An ambulance man on duty at the Holborn Oasis swimming pool, London, suffering in the July heat. (Photo by Keystone/Getty Images). 1964

Children escape the heat of the summer by sitting under a small cascade, where Roman emperors bathed. (Photo by Hulton Archive/Getty Images). 1950

Three women on Blackpool promenade during a heatwave. One wears a divided skirt and the other a straight skirt, both over swimwear. The middle one has a “copy” of the Letty Lynton dress made popular by Joan Crawford in the film of that name. Adapted for the mass market the triple row of frills at the hem are matched by frills at the shoulder forming cap sleeves. (Photo by E Dean/Getty Images). 1934

Two children jumping through a water hydrant's shower on a New York street. They have come from a neighbouring co-educational playgroup organised by the city's Police Department. (Photo by Orlando/Getty Images). 1950

Children playing in the sandpit at a Dr Barnardo's Home in Barkingside during a heatwave. (Photo by Fox Photos/Getty Images). June 1934

Schoolboys from Netherton Nursery School in Chelsea, London, cool off during a heatwave. (Photo by Reg Speller/Fox Photos/Getty Images). 1st July 1949

Too warm for March for the passer by who is mopping his brow as he reads a thermometer in Smithfield Market, London which reads 70 fahrenheit. (Photo by Ward/Fox Photos/Getty Images). 24th March 1938

Three women keep cool during a heat wave by moving a park bench into the water in Central Park, New York. (Photo by Keystone Features/Getty Images). September 1961

A water cart man turns the water main on a group of boys to help them cool off in a street in Westminster, London during a heatwave. (Photo by Fox Photos/Getty Images). August 1930

People paddling in the Thames during the heat wave. (Photo by David Savill/Topical Press Agency/Getty Images). 22nd June 1935

Children enjoy a cooling drink from the fountain on Clapham Common. (Photo by H. Allen/Topical Press Agency/Getty Images). 6th August 1937

A Parisian relaxes in the heat outside a cafe, his feet soaking in a pan of water. (Photo by Keystone/Getty Images). Circa 1950

Onlookers lean over the bridge to watch people paddling in the Serpentine to cool off during a heatwave in London. (Photo by Topical Press Agency/Getty Images). 1911

Two young children at Dr Barnardo's sheltering under an umbrella from a garden shower. (Photo by Fox Photos/Getty Images). 21st June 1934

A three year old boy mischievously turns off a fountain, during a heatwave, at Hampton Court Palace gardens, London. (Photo by George Konig/Keystone Features/Getty Images). 22nd August 1947

Holiday makers in Clacton-on-Sea relax in the heat by lying on top of their parked cars. (Photo by Evening Standard/Getty Images). 31st July 1967

Children in a New York street playing with a water hydrant. (Photo by Peter Keegan/Keystone/Getty Images). Circa 1970

Christine Child and Francis Pidgeon on the roof of Piccadilly Theatre during a break in rehearsals for “The Crooked Mile”. (Photo by John Franks/Keystone/Getty Images). 7th July 1959

East Berlin children cooling off on the sidewalk. (Photo by Keystone/Getty Images). 14th July 1956

New York children cooling off under the spray of a fire hydrant during a heat wave. (Photo by Peter Keegan/Keystone/Getty Images). Circa 1945

A bus driver cools off at the bus station during a very hot summer in Budapest. (Photo by Keystone/Getty Images). 18th July 1963