As the smoke eases, firefighters then move into the forest on foot to try and contain the latest flare-up.
They are the principal concern for the thousands of crews and volunteers combating the wildfires that have raged here for a week, forcing tens of thousands of residents and tourists to flee.
As temperatures peak at around 40C, fires restarting on their own are a constant threat.
After 20 minutes or so, the one we are watching is brought under control, only for another to suddenly emerge on the opposite side of the road.
"Leave now!" shouts an understandably irritable officer as he drives past. The smoke is becoming thicker and more aggressive. Indeed, time to leave.
Such is the vast scale of the infernos ravaging France's south-western Gironde region, that it is not always obvious what direction the smoke is coming from.
It simply descends as you travel west from Bordeaux along empty roads and through deserted villages.
The soil is powder-like and covered in endless pinecones and dried leaves. It explains how the wildfires have spread at the rate they have.
"If it's too late, at least we tried," said a defiant Hugo, 26, as he refilled his water tank. "Fifty thousand hectares has already been destroyed, what will we tell our children?"
Hugo grew up in the area and has returned from his home in Bali to watch his mother's house in the village of Arès, which is perilously close to the wildfires.
"It's horrible, it's our home, it's our region, it's our forest, it's where we grew up, it's where our family live, where we live, it's horrible. I feel a lot of sadness," Maëlys, 23, told us, her face covered in soot.
"I am a nurse and I'm here to help," she added. Maëlys said her friends own big water tanks, which they then use to try to put out fires that flare-up to prevent them from spreading.
"In the morning I am at the hospital working, and in the afternoon I'm in the forest helping," she said.
