FIRE crews battled a mega-fire four times the size of Paris in south-west France while facing tinderbox temperatures set to climb above 40°C today.

The heat wave and forecast winds could hamper progress against the blaze that has forced 220,000 people from their homes, authorities for the Gironde region around Bordeaux said.

In a Wednesday morning update on the huge firefighting effort, Gironde authorities said the situation overnight had been “calm” and that the blaze hadn’t spread — although it’s still not contained a week after it started.

The onset of heat-wave temperatures and winds heightened the risk of flames flaring again.

On Tuesday, Gironde authorities ordered 4,000 more people evacuated from tourist sites along the Atlantic coast, widening what may be France’s largest peacetime evacuation.

“The situation remains complicated. That’s clear. We’re not out of the woods,” Gironde prefect Sophie Brocas said on Tuesday evening. But she also gave the go-ahead for 60,000 evacuees to return to their homes in three Bordeaux suburbs that haven’t burned.

The opposing movements — thousands ordered out of coastal resorts while those returning were told to be on the alert — underscored how precarious the fire’s hold remained.

Across France and Spain, roughly 330,000 people have been driven from homes and holiday sites by huge wildfires. 

More than 448 square miles have burned across France this year, according to the Interior Ministry.

Europe is the world’s fastest-warming continent, heating at more than twice the global average, according to the European Union’s Copernicus climate service. 

Western Europe recorded its hottest June on record, with extreme heat and widespread dryness contributing to the spread and intensification of fires in France and Spain, Copernicus said.

Meanwhile, thousands of people evacuated in Spain started to return home on Wednesday as the government said they were working to contain some of the worst forest fires in the country’s modern history.

Late on Tuesday, the government had lifted evacuation orders on more than a dozen municipalities in the Madrid and Avila areas, the epicentre of wildfires that had forced tens of thousands to be displaced.

“24,000 evacuated individuals have been able to return to their homes, and another 20,000 have been released from confinement in the Community of Madrid,” government delegate Francisco Martin Aguirre said on social media late on Tuesday.

“Work continues to consolidate the progress made throughout the day in tackling the fire. The return of evacuees is proceeding without incident.”