Rains over southern California have the potential to cause dangerous toxic runoff in areas burned by the devastating wildfires.
Most of the region is forecast at least an inch of rain, but the National Weather Service has warned of localised cloudbursts that could cause mudslides.
Flood watches are now in effect for areas including Pacific Palisades, Altadena and Castaic Lake.
A portion of the Pacific Coast Highway was closed due to mudflows in Topanga Canyon.
“All these fresh burns are very susceptible to rapid runoff,” Joe Sirard, a local meteorologist, told AP News.
“What that means is we have a fairly high danger of mud and debris flows once we get above those thresholds.”
Officials have warned that the ash left by the fires is extremely toxic, made up of burnt-out cars, electronic devices, batteries, building materials and household items. It contains “pesticides, asbestos, plastics and lead.” Residents have been advised to wear protective equipment, including masks, while cleaning up.
As well as bringing danger, the rains could also bring relief and help firefighters bring the remaining wildfires under control.
The Palisades fire, the largest of the wildfires by far, which has killed at least 11 people, was at 90% containment on Sunday. The Eaton fire, which has killed 16, was at 98% containment. The Hughes Fire was at 95%.
The rain brings to an a near-record streak of dry weather for southern California. Much of the region has received less than 5% of the average rainfall for this point in the water year, which began on 1 October.