Thousands of firefighters struggled to put out a dozen wildfires raging in northern Portugal and central Spain through the night and into Wednesday, in the largest wave of blazes in the Iberian Peninsula so far this year after weeks of summer heat.

The largest wildfire has been burning in the wooded, mountainous Arouca area – some 300 km (185 miles) north of Lisbon – since Monday, leading to the closure of the scenic trails of Passadicos do Paiva, a popular tourist attraction.

Some 800 firefighters and seven waterbombing aircraft tackled the blaze.

“There was a huge effort during the night, so now we have a somewhat calmer situation,” Civil Protection Commander Helder Silva told reporters, cautioning that shifting strong winds and a difficult terrain meant their work was far from over.

“It’s a very large wildfire in areas with difficult access,” he said.

Further north, a blaze has been raging since Saturday in the Peneda-Geres national park near the Spanish border, enveloping nearby villages in thick smoke that led to orders for residents to stay at home.

Portuguese firefighters managed to control two large fires that started on Monday in the central areas of Penamacor and Nisa. Authorities said the Penamacor blaze had destroyed 3,000 hectares (7,413 acres) of forest.

In Spain’s central province of Avila, shifting gusts of wind hindered efforts by firefighters and a special military unit, emergency services said. Residents in the village of El Arenal, about 100 km (62 miles) west of Madrid, were advised to remain indoors due to heavy smoke.

In Mombeltran near Avila, farmer Blas Rodriguez fought back tears as he walked among scorched trees, his olive grove devastated by the fire.

“This land belongs to my father. It burnt 16 years ago but the olive trees were spared from the fire… this time there is no way to save them, everything is completely burnt,” he told Reuters.

In the western province of Caceres, the fire has affected 2,500 hectares, prompting evacuations from homes scattered across the Caminomorisco area, authorities said.

Hot and dry summers are common across the region, but more intense heatwaves have contributed to destructive wildfires in recent years amid fast-rising temperatures around the globe. Portugal and Spain had the hottest June on record.