LOS ANGELES (AP) — A powerful winter storm swept across Southern California on Wednesday, with heavy rain threatening mudslides and debris flows in areas scorched by wildfires, bringing near white-out snow conditions in the mountains and hazardous travel for millions of holiday drivers.

Forecasters said Southern California could see its wettest Christmas in years and warned about flash flooding. Areas scorched by January’s wildfires were under evacuation warnings, and Los Angeles County officials said Tuesday they were going door to door at about 380 especially vulnerable homes, ordering residents to evacuate because of the risk of landslides and debris flows.

Areas along the coast, including Malibu, were under flood warnings Wednesday, local officials said. Parts of Santa Barbara and Ventura counties were also watching for potential flooding. Other parts of Southern California were under wind and flood advisories. Further north, much of the Sacramento Valley and the San Francisco Bay Area were under a flood watch and high wind warning.

Minor roadway flooding and downed trees were reported across the state Wednesday.

Early Wednesday morning, the Los Angeles Fire Department rescued a man trapped in a drainage tunnel in northwest LA that led down to a river.