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.”

A new fast-moving wildfire has erupted in Los Angeles County, triggering evacuations in a region already reeling from the most destructive fires in its history. The Hughes fire ignited north of the city on Wednesday afternoon,