Millions of people across the northern Gulf Coast braced Tuesday for a rare winter storm that’s expected to scatter heavy snow, sleet and freezing rain around the Deep South as a blast of Arctic air plunges much of the eastern U.S. into a deep freeze.

The South is bracing for a major winter storm, most of the nation remains gripped by extreme cold, and high winds could fan flames in California.

Critical fire weather with wind gusts up to 60 mph (97 kph) was also forecast for Southern California communities stretching to San Diego, with residents urged to take steps to get ready to evacuate such as creating an emergency kit and keeping cars filled with at least a half tank of gas.

Experts explain why Southern California is experiencing its most devastating winter wildfires in decades and what this could mean for the future of fire seasons.