Extreme heatwaves are sweeping Europe and the United States with some people being treated for third degree burns.

In Phoenix, Arizona, mobile clinics are treating homeless people suffering from third-degree burns and severe dehydration.

The city has already endured 15 days in a row of temperatures exceeding 43.3 degrees Celsius.

In the desert city of Palm Springs, homeless people have been left to deal with the extreme heat themselves, with only 20 beds available in the sole shelter.

Roman Ruiz, the city's homeless services coordinator, told CBS News homeless residents struggle in normal heat to find enough shade.

"I don't know how anyone can do it really," he said.

"I feel so bad, and yet there's not much I can do."