The latest wildfires have already devastated more than 17,000 hectares (42,000 acres) of land — twice the size of Manhattan — across the three countries where temperatures in some places were predicted to touch 40C on Sunday.

Authorities registered thousands of excess deaths during one of Europe’s worst heatwaves in June, and with more extreme weather on the way, France’s Interior Minister Laurent Nunez has already expressed concern that the annual summer wildfire season had started a month early.

A fire near Spain’s northeastern Costa Brava coast burned more than 2,200 hectares in two days and firefighters said their operation on Sunday would be “complicated” by rising temperatures and the many “smoking hotspots” within the fire’s perimeter.

Firefighters “worked tirelessly throughout the night to consolidate the perimeter of the La Bisbal d’Empordà forest fire, which is now stabilized,” said a Catalunya fire service statement.

Catalunya regional government president Salvador Illa said that a man had been detained in connection with the fire which has badly hit the Gavarres protected natural area between Barcelona and the French border.

Nearly 600 French firefighters have been mobilised to contain a wildfire that has burned more than 1,000 hectares on a mountainside at Trevillach, about 36 kilometres (20 miles) east of Perpignan.

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More trouble ahead

Roads in the region have been closed and the authorities have ordered mayors to open emergency shelters for people who could be forced to flee their homes.

Another 300 French firefighters battled another forest fire in a mountainous district of the southeastern Drome department.

In Portugal, emergency services said they had controlled “80 percent” of a wildfire that has devastated some 13,000 hectares of forest and scrub land in the north of the country.

A senior civil protection officer Jose Costa told AFP that the fire had spread 35km since it started on Thursday and that 1,200 firefighters had been involved in the battle.

Spain and Italy sent reinforcements and water carrying planes after Portugal appealed for help to fight the inferno that has left nine people injured by burns.

Several regions across Portugal, Spain and southern France stepped up heat alerts on Sunday as temperatures rose again. On Monday the latest heatwave was expected to move north. Forecasters say it could last until next weekend.

Western Europe has already seen heatwaves this year in May and June that would have been “virtually impossible” without climate change, the World Weather Attribution group of scientists said.

Following a two-week surge in temperatures in June, France said there had been more than 2,000 extra deaths than usual in just one week, while Spain and Belgium each reported more than 1,000.

Authorities in several countries fear more summer trouble ahead.

“Climate change is here, we are living the consequences and it is only the start of July,” said French fire service Colonel Eric Belgioino as he made an appeal for people near the Pyrenees inferno to take precautions to avoid starting fires.

“The season is going to be long for the soldiers fighting fires. You have to help us,” he said.