People swim at the sea in Havana, April 28, 2015. On Sunday, Cuba registered a temperature of 39.7 degrees Celsius, 0.1 degrees less than the island's historic record, according to Jose Rubiera, Director of the National Forecast Center of the Institute of Meteorology of Cuba. REUTERS/Alexandre Meneghini TPX IMAGES OF THE DAY

People enjoy the sea early in the morning in Havana, April 28, 2015. On Sunday, Cuba registered a temperature of 39.7 degrees Celsius, 0.1 degrees less than the island's historic record, according to Jose Rubiera, Director of the National Forecast Center of the Institute of Meteorology of Cuba. REUTERS/Alexandre Meneghini

Retired computer programmer Esperanza Delgado (C), 61, smokes a cigarette before swimming in Havana, April 28, 2015. On Sunday, Cuba registered a temperature of 39.7 degrees Celsius, 0.1 degrees less than the island's historic record, according to Jose Rubiera, Director of the National Forecast Center of the Institute of Meteorology of Cuba. REUTERS/Alexandre Meneghini

Retired chef Edita Mijares, 67, swims in the sea in Havana, April 28, 2015. On Sunday, Cuba registered a temperature of 39.7 degrees Celsius, 0.1 degrees less than the island's historic record, according to Jose Rubiera, Director of the National Forecast Center of the Institute of Meteorology of Cuba. REUTERS/Alexandre Meneghini

Retired Mechanical Engineer Enrique Biosca, 76, looks to the camera before entering the sea in Havana, April 28, 2015. On Sunday, Cuba registered a temperature of 39.7 degrees Celsius, 0.1 degrees less than the island's historic record, according to Jose Rubiera, Director of the National Forecast Center of the Institute of Meteorology of Cuba. REUTERS/Alexandre Meneghini

Retired school teacher Ilda Fortuna, 67, sunbathes at the seafront in Havana, April 28, 2015. On Sunday, Cuba registered a temperature of 39.7 degrees Celsius, 0.1 degrees less than the island's historic record, according to Jose Rubiera, Director of the National Forecast Center of the Institute of Meteorology of Cuba. REUTERS/Alexandre Meneghini

A woman talks to a friend (unseen) before entering the sea in Havana, April 28, 2015. On Sunday, Cuba registered a temperature of 39.7 degrees Celsius, 0.1 degrees less than the island's historic record, according to Jose Rubiera, Director of the National Forecast Center of the Institute of Meteorology of Cuba. REUTERS/Alexandre Meneghini

Retired biologist Rosa Cornide, 81, swims at the sea in Havana, April 28, 2015. On Sunday, Cuba registered a temperature of 39.7 degrees Celsius, 0.1 degrees less than the island's historic record, according to Jose Rubiera, Director of the National Forecast Center of the Institute of Meteorology of Cuba. REUTERS/Alexandre Meneghini

A man prepares to enter the sea in Havana, April 28, 2015. On Sunday, Cuba registered a temperature of 39.7 degrees Celsius, 0.1 degrees less than the island's historic record, according to Jose Rubiera, Director of the National Forecast Center of the Institute of Meteorology of Cuba. REUTERS/Alexandre Meneghini