Containing wildfires—never mind extinguishing them—in parched and windy conditions can be monstrously difficult. Dry vegetation is rocket fuel for blazes and wind both feeds the flames and spreads the embers. “The winds are like pointing an air blower at a fireplace,” says Gershunov, “except it’s not contained and it’s on a much larger scale.”

Authorities have issued warnings over strong winds in California that posed a risk to the fire-affected region. Firefighters from other states as well as Canada and Mexico have been called in.