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.”

More powerful winds were expected to trigger new wildfires that could set back the recent progress made in containing blazes in the Los Angeles area that have destroyed thousands of homes and killed at least 24 people.

Trying to estimate when the wildfires will be contained is largely guesswork. Yet the foremost factors are clear: wind and rain, or the lack thereof.