Rain was falling across Southern California on Sunday, bringing some relief to thousands of firefighters battling multiple major blazes for nearly a month in the Los Angeles area, but also prompting new threats of floods and mudslides across burn-scarred lands.

After weeks of windy and dry weather, rain has fallen in parched Southern California and is expected to aid firefighters who are mopping up multiple wildfires. But potentially heavy downpours on charred hillsides could bring new troubles such as toxic ash runoff.