If the rain falls at a steady, lighter rate, Southern California could be in good shape. That could mean enough rain to help ease the firefighting strain, but not enough to trigger another potential disaster. Heavier rain could mean the chance for flash flooding or mudslides over fresh burn scars.

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 in Southern California is expected to help firefighters responding to multiple wildfires, but potentially heavy rain on burned hillsides could cause toxic ash runoff.