A flash-flood watch went into effect at 10 a.m. Sunday that includes fire-scarred areas of Souther California, with forecasters boosting their predictions for rainfall that carry the risk of significant flash flooding and debris.

Much-needed rain has begun to fall over Southern California, bringing relief to the drought-stricken region but also the threat of toxic runoff.

Rain on its way to the Los Angeles area will be a welcome relief to firefighters still battling multiple catastrophic wildfires, but officials warned Sunday that flash floods and potential debris flows could be the trade-off.