There were two outages in the Costa Mesa and Newport Beach area that occurred just before 1:30 a.m., according to Southern California Edison spokeswoman Gabriela Ornelas.
Initially, 3,470 customers lost power, but by 12:30 p.m. there were only 805 customers still waiting for the electricity to be restored, she said.
Edison expects all of the power to be restored by 3:30 p.m., she said.
Ornelas said the outage appeared to have been caused by mylar balloons that got caught in a power line.
Edison officials advise residents to tie metallic balloons to a weight and keep them indoors when possible.
They should be punctured before disposal and not be released outdoors, and no one should ever try to retrieve one that gets tangled in electrical equipment.