The Los Angeles Department of Water and Power on Saturday evening said restoring power for the thousands of residents who lost electricity during the heat wave would take longer than the agency initially estimated.
Some 37,000 customers experienced outages as of 10 p.m., according to the department. Saturday's "peak electricity use" resulted in the second highest weekend day in the city, the agency said.
Estimated restoration time increased from 12 to 24 hours to 24 to 48 hours with some complex outages possibly taking longer than 48 hours, according to LADWP.
"Unrelenting weather conditions and high energy demand continue to strain equipment," the department said.
The agency said some of the communities most impacted by the outages included customers in Koreatown (4,900), Westlake (4,600) and Los Feliz (3,300).
Sherman Oaks resident Elizabeth Oaks said she had been waiting more than 24 hours for her power to be restored.
"It's miserable," Oaks said.
Since the heat started on Friday, power has been restored to about 20,000 customers with an average duration of 11 hours.
Some 34,500 customers experienced outages as of 8 a.m., according to the agency. Friday's record-breaking temperatures led to "unprecedented peak electricity demand" in the city, the department said.
"We have extra crews working hard on multiple outages during this heat storm. We really appreciate our customers’ patience and understanding," the agency said in a tweet.
The outage number decreased to 32,800 customers as of 3 p.m. Saturday, according to a department news release.
Some Twitter users said they have not had electricity for at least 12 hours.
At least 5,800 customers were initially impacted in Westlake, 4,400 in Koreatown, 2,000 in Beverly Grove and 3,000 in Encino, according to LADWP.
At 9:37 p.m. the agency said most customers in Encino had their power restored.
The agency urged residents to reduce their electricity use between 2 p.m. and 9 p.m. on Saturday.
Southern California Edison also initially reported power outages affecting more than 8,000 customers in L.A. County, 2,159 in Orange County and 1,251 in San Bernardino County.
There were 17,000 customers without power as of 7 p.m. Saturday, the agency said in a news release.
The region had record-breaking heat on Friday, with downtown L.A., Burbank, Van Nuys and Woodland Hills reaching triple-digit temperatures.
Slightly lower temperatures were forecasted for the weekend. An excessive heat warning was set to expire at 9 p.m. Saturday.
KTLA's Wes Woods II contributed to this report.