In the city of Los Angeles alone, 1,300 customers werewithout power, the Department of Water and Power said.
DWP said in a statement that it is common for the first significant storm of the season to cause power outages when "dried palm fronds, tree branches and other debris fall and make contact with power lines."
About 2,870 Southern California Edison customers were without power Thursday afternoon.
In the Inland Empire, more than 5,000 customers are without power, Edison said, with the most affected in Moreno Valley. In Ventura, 53 customers were without power, and in Orange County, 298 customers were without power.
Crews are working to restore power as soon as possible, officials said.