Wildfires have continued to burn across Portugal, Spain, France and Croatia as large parts of Europe face a persistent heatwave pushing temperatures into the mid-40Cs.

In Portugal’s central Leiria district firefighters battled to control blazes that have been fanned by strong winds. Portuguese Prime Minister Antonio Costa said during a briefing with the national meteorological institute IPMA: “It is absolutely crucial we avoid new events because it leads to the exhaustion of firefighters and all others … who are doing their best to control the situation.”

In western Spain a fire that started in the Extremadura region on Tuesday crossed into Salamanca province in the region of Castile and Leon, forcing the evacuation of 49 children from a summer camp on Thursday. Regional authorities said more than 4,000 hectares (9,900 acres) of land had been burned.

On Croatia’s Adriatic Coast, firefighting planes were called in to dispense water over burning forests whilst troops were enlisted in to help firefighters in the battle to contain three major wildfires around Zadar and Sibenek.

In southwestern France more than 1,000 firefighters backed by nine water-dropping planes battled two wildfires that started on Tuesday and have already burnt 5,300 hectares.

Thousands of people were also evacuated from homes on Turkey’s southwestern Datca peninsula due to a fire that started on Wednesday which was hit with strong winds overnight and threatened residential areas.

A study in the journal Nature found that the number of heatwaves in Europe has increased three-to-four times faster than in the rest of the northern mid-latitudes, such as the United States and Canada, due in large part to the jet stream air current splitting into two parts for longer periods.

The study’s co-author Kai Kornhuber, a climate scientist at Columbia University, told Reuters: “Europe is very much affected by changes in atmospheric circulation. It’s a heatwave hotspot.”