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

Rain was falling across Southern California on Sunday, bringing some relief to thousands of firefighters who have been battling multiple major wildfires in the LA area.

There is a 10% to 20% chance of flash flooding and landslides in some recently burned areas of Los Angeles County, forecasters say, including the Palisades and Eaton fire areas.

The National Weather Service issued a flood watch effective from 4 p.m. Sunday to 4 p.m. Monday for areas in or near burn scars created by the Palisades Fire, Eaton Fire, Hughes Fire and Bridge Fire, the latter blaze of which burned 56,000 acres last fall.

The wet weather will bring relief to Southern California after a prolonged period of dryness, but there’s concern that any bursts of heavy rainfall could cause flooding.