A polar bear swims in the water at the zoo in Hannover, Germany, Wednesday, June 26, 2019. A heatwave hits Germany and Europe. (Hauke-Christian Dittrich/dpa via AP)

People cool off in the fountain of the Trocadero, as the Eiffel Tower is visible in background, in Paris, Tuesday, June 25, 2019. Authorities warned that temperatures could top 40 degrees Celsius (104 Fahrenheit) in some parts of Europe over the coming days, the effect of hot air moving northward from Africa. French Health Minister Agnes Buzyn said more than half of France is on alert for high temperatures Tuesday and the hot weather is expected to last until the end of the week. (AP Photo/Alessandra Tarantino)

A man enjoys the sunrise on the Drachenberg over Berlin, Germany, Wednesday, June 26, 2019. Temperatures of up to 38 degrees are expected in the German capital. (Kay Nietfeld/dpa via AP)

People cool off in the fountain of the Trocadero, in Paris, Tuesday, June 25, 2019. Authorities warned that temperatures could top 40 degrees Celsius (104 Fahrenheit) in some parts of Europe over the coming days, the effect of hot air moving northward from Africa. French Health Minister Agnes Buzyn said more than half of France is on alert for high temperatures Tuesday and the hot weather is expected to last until the end of the week. (AP Photo/Alessandra Tarantino)

Young people enjoy the evening on lake Walensee, on Tuesday, June 25, 2019, in Walenstadt, Switzerland. The country was hit by a heatwave with temperatures up to 39 degrees celsius. (Gian Ehrenzeller/Keystone via AP)

People cool off in a fountain during a hot summer day, in Pamplona, northern Spain, Tuesday, June, 25, 2019. Hot air from Africa is bringing a heat wave to Europe, prompting health warnings about Sahara Desert dust and exceptionally high temperatures in Spain. (AP Photo/Alvaro Barrientos)

Tourists climb the steps leading to the Sacre Coeur basilica Wednesday, June 26, 2019 in the Montmartre district of Paris. More than half of France is on alert for high temperatures and the hot weather is expected to last until the end of the week. (AP Photo/Kamil Zihnioglu)

A sign shows 37 degrees Celsius at a building in the city of Stuttgart, Germany, Wednesday, June 26, 2019. Germany and Europe is hit by a heatwave with temperatures near 40 degrees. (Marijan Murat/dpa via AP)

A tourist shelters under an umbrella Wednesday, June 26, 2019 in the Montmartre district of Paris. More than half of France is on alert for high temperatures and the hot weather is expected to last until the end of the week. (AP Photo/Kamil Zihnioglu)

An animal keeper puts suntan lotion on a lowland tapir during the hot summer weather in an animal park in Hodenhagen, Germany, Wednesday, June 26, 2019. Germany faces a heatwave with high temperatures and UV radiation. (Mohssen Assanimoghaddam/dpa via AP)

Ring-tailed lemur (Lemur catta) lick big blocks of ice candy, composed of a mix of vegetables frozen in ice, during warm temperatures at the Zoo in Erfurt, Germany, Wednesday, June 26, 2019. Weather forecasts predict sunny weather with temperatures of up to 38 degrees (100,4 degrees Fahrenheit) in Germany. (AP Photo/Jens Meyer)

In Iceland horse is sprayed with water at a stud in Wehrheim near Frankfurt, Germany, on a hot and sunny Wednesday, June 26, 2019. Hot temperatures are expected all over Europe. (AP Photo/Michael Probst)