People in southern California are sandbagging in anticipation of heavy rain.
This is what constitutes flood precautions in southern California, at least as far as the Associated Press is concerned.

You’re probably going to need more, Richard.
It’s a very real threat because wildfires months ago could lead to mudslides. But none of the sandbag walls — as depicted in this video — are going to stop much, at least the way they’re constructed.