About 220,000 people have been evacuated in France, while in Spain more than 115,000 people have been evacuated and a further 30,000 ordered to shelter in place, authorities said.
In France, fires have ravaged the Cap Ferret peninsula on the Atlantic coast, a popular tourist destination, and spread through areas surrounding Bordeaux, where firefighters were trying to prevent the flames from reaching the regional capital.
Bordeaux Mayor Thomas Cazenave said the fire was about 15km away from the entry points to the main city.
"We have a fire that is not under control and which is moving in the direction of the city area," Interior Minister Laurent Nunez told France 2 TV on Sunday evening. "The overall situation is very unfavourable, we are in a situation that is unprecedented."
Cazenave said on Sunday that there were no plans to evacuate Bordeaux, whose wider metropolitan area has a population of about 850,000. Nunez said authorities would continue to assess the situation calmly and realistically.
As the blaze advanced, police went door-to-door overnight in the municipalities of Marcheprime and Cestas, evacuating residents one home at a time. French authorities released footage showing officers knocking on doors in the dark and urging people to leave.
In Spain, Prime Minister Pedro Sanchez visited fire-hit areas in Avila, one of three central provinces affected by major blazes, alongside Madrid and Toledo.
Flames have devastated more than 50,000 hectares of countryside in Avila, making it the biggest wildfire in Spain's recent history, according to Environment Minister Sara Aagesen.
A separate blaze in Spain's eastern Castellon province has ravaged over 4300 hectares, regional authorities said.
"The fire is out of control, it's very difficult to extinguish from a technical standpoint, especially because of the adverse weather conditions that will continue throughout the day," the regional leader of Valencia, Juanfran Perez, told reporters near the site.
The fires are the latest disasters linked to prolonged drought and successive heatwaves that scientists say have been intensified by climate change. In both Bordeaux and Avila, July high temperatures have averaged 32C, almost 6C above the month's normal high between 1961 and 1990, according to the Reuters Climate Monitor.
Under the European Union's civil protection mechanism, Greece and Italy have each sent two Canadair firefighting aircraft to Spain, while Portugal has deployed more than 100 military personnel along with equipment.
Two more planes will arrive "as soon as possible" from Turkey, the Spanish interior ministry said on X.
Sanchez said his government would on Tuesday declare a civil protection emergency for the central provinces plagued by the wildfires, unlocking additional recovery funding.
More than 150,000 hectares have burned across Spain since January, he said, six times the area destroyed during the same period last year.
In the highlands of Scotland, as many as 500 firefighters have been dealing with a large blaze within Cairngorms National Park since July 15.
Residents of the village of Nethy Bridge, who were evacuated on Friday evening after a change in the weather conditions, were allowed to return to their homes late on Saturday.
In Italy, several bush fires forced the closure for several hours of a southern section of the Rome ring road as well as of a motorway leading into the capital, causing major traffic disruption.
In Italy's southern Puglia region, tourists were evacuated from seaside resorts due to a large wildfire in the Gargano area, the national fire department said. Some were taken away via sea by the coast guard, the ANSA news agency added.
with EFE and DPA
