Watch: Locals, tourists in Croatia swap sunscreens for mud as second record heatwave hits Europe

In Croatia, 56 firefighters with 20 vehicles and three aircraft, struggled to contain a bushfire that was spreading rapidly due to strong southerly winds.

Swathes of the Balkans sweltered in temperatures above 40 degrees Celsius (104 Fahrenheit) on Thursday in a heatwave named "Cerberus", after the three-headed dog of the underworld in Greek mythology, that has fanned across Europe.

A couple covered in mud that is believed to be curative sit at the Queen's beach in Croatia. (Reuters)

In Croatia, 56 firefighters with 20 vehicles and three aircraft, struggled to contain a bushfire that was spreading rapidly due to strong southerly winds near the Adriatic town of Sibenik.

In the country's Adriatic resort of Nin, dozens of beachgoers covered themselves in thick black mud believed to have medicinal properties and an effective sunscreen.

"It (mud) is definitely better than sun screen, I think protection factor is much better," said a tourist from Slovakia who only gave his name as Josef.

Meteorologists and doctors in Montenegro, Bosnia and Serbia, warned people to stay indoors or drink plenty of liquids if venturing outside.

Temperatures were expected to stay around 40 degrees Celsius across the region into next week.