“The situation is still complex; our goal is to defend people’s lives,” Prime Minister Pedro Sánchez of Spain said at a news conference on Saturday, at a command center west of Madrid. He said there was a “window of opportunity” this weekend to fight the fire as temperatures eased, but urged caution as strong winds and dry thunderstorms caused by the fires could further complicate firefighters’ work.

Prime Minister Sébastien Lecornu of France warned that the blaze in Gironde, which had burned about 35,000 acres as of Friday night, was a fire “that generates its own winds, accelerates its spread and can abruptly change direction.”

That fire had burned 53 homes as of Friday night, Laurent Nuñez, France’s interior minister, told the broadcaster TF1. The fire was very hard to control because of changing winds, he added.

Mr. Nuñez said that the fire was moving east, toward Bordeaux, famed for its wineries. Around 800,000 people live in the city and its surrounding area.

Bordeaux itself was not under threat, Mr. Nuñez said. Still, on Saturday, the prefect for the Gironde area ordered the evacuation of several of Bordeaux’s western suburbs as a precautionary measure. One includes the city’s airport.

On Friday, as smoke and ash lingered in the air, the French authorities ordered the evacuation of the entire Cap Ferret Peninsula, a popular Atlantic holiday destination, forcing tens of thousands of holidaymakers to rush away by boat or by car.

The fires in France and Spain are part of a broader wave of wildfires this summer across Europe, where repeated heat waves since May have brought extreme temperatures. Last month was the hottest June on record in Western Europe, according to Copernicus, a European Union monitoring agency.

Connecting a specific heat wave or fire to global warming is hard to do, but experts agree that human-caused climate change is behind increasingly high temperatures that have made wildfires in general more destructive.

In Spain, the authorities declared a national emergency in a region near Madrid. Wildfires in the mountains west of the city remained active and out of control on Saturday, although a drop in temperatures overnight helped firefighters to keep them from spreading.

“This is the worst wildfire in the Madrid region’s history,” Isabel Díaz Ayuso, the regional president, said on Friday. “This is not over.”

• France: The authorities have mobilized the military, with 500 troops already on the ground and 500 more to join on Saturday, Mr. Lecornu said. He urged people to heed evacuation orders. “We will take no risks when it comes to the safety of the French people,” he said.

• Spain: Mr. Sánchez said at the news conference on Saturday that more than 321,000 acres had been scorched in Spain since the beginning of the year, compared with an average of 247,000 acres per year over the past decade. “The climate emergency is worsening and exceeding scientific projections,” he said.