Rainfall has provided relief to wildfire-stricken Southern California but posed new threats of toxic ash runoff and debris flows. Authorities are expediting cleanup efforts and implementing flood-control measures to mitigate environmental impacts.

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.

Rains have finally arrived in Southern California, aiding firefighting efforts in the region. However, the weather also raises new concerns about potential mudslides and toxic runoff on burn-scarred hillsides.