Dive Brief:

• Tens of thousands of Southern California residents went without power this weekend as a heat wave battered the utility systems, causing widespread and recurring outages.

• The Los Angeles Department of Water and Power said Monday it was still restoring power to more than 15,000 customers after more than 60,000 lost electricity service as temperatures entered triple digits this weekend. Southern California Edison (SCE) reported about 19,000 outages on Saturday, with more than 2,000 customers still without power Monday.

• Utilities blamed the record heat for causing problems with distribution system equipment and the state did not appear to experience major outages related to generation availability. The California ISO issued restricted maintenance notices throughout the weekend, but no emergency notifications.

Dive Insight:

Generation availability in California — particularly fuel supply to gas plants — has sparked reliability concerns at CAISO and the Federal Energy Regulatory Commission, but utilities there say year’s first wave of major outages is due largely to the strain that high temperatures and record power demand put on their distribution systems.

As of Sunday night, LADWP said it had restored power to more than 57,000 customers, but "continued overloading of circuits has slowed restoration progress and led to recurring outages in some neighborhoods," leaving more than 26,000 without power.

Monday morning, LADWP said on Twitter that overnight work had reduced that number to about 15,000 customers. The utility urged customers to reduce power usage, "especially in these neighborhoods where outages have been restored, but which have lost service again due to high demand for electricity which strains neighborhood distribution equipment."

LADWP serves 1.5 million residents in Los Angeles. The utility said its peak demand exceeded 5,700 MW on Saturday — the second-highest weekend day in its history — and Friday’s peak demand of 6,256 MW set a new record for a July day.

SCE, which serves 15 million customers surrounding Los Angeles, reported fewer outages, but said Saturday that heat-related issues had cut power to about 19,000. The utility also urged customers to reduce usage and said that it staffed extra restoration crews in anticipation of the heat.

Even with higher demand in the south, the state did not fall short on generation capacity. CAISO requested on Thursday that generators delay scheduled maintenance in anticipation of the heat, but did not issue a Flex Alert to encourage voluntary power conservation, nor any emergency notifications that it would use power reserves.

The larger test for the state’s grid will likely come later this summer, however, as temperatures continue to rise and California’s fire season heats up. LADWP’s peak demand record of 6,502 MW was reached at the end of last August, and officials from CAISO warn that wildfires fed by high temperatures could disrupt power supply from generators, leading to forced outages.