Heavy rains in Southern California aid firefighters battling wildfires but increase risks of mudslides and toxic ash runoff. Flood watches are in effect for burn zones in Pacific Palisades, Altadena, and Castaic Lake. The National Oceanic and Atmospheric Administration warned of localized flash flooding. As of Monday morning, the largest fire, the Palisades, was 90% contained. Schools in Malibu were closed due to dangerous conditions. Officials emphasized that rain can quickly trigger runoff and debris flows in fresh burn areas, underscoring the ongoing hazard despite the firefighting progress.