California avoids large blackouts from heat wave but shutoffs could come Labor Day over wildfire risk

14,800 firefighters are battling 23 major wildfires in California

Millions in California avoided rolling blackouts on Sunday as record-breaking temperatures have strained the state's electric grid, but power outages may come on Labor Day as heat lingers and gusty winds bring the threat of wildfires.

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The California Independent System Operator (ISO), which manages most of the state's electric flow, had warned that up to 3 million customers faced power outages if residents didn't curtail their electricity usage.

"Thank you, California, for protecting the grid again," the ISO tweeted.

CALIFORNIA POWER TROUBLES, ROLLING BLACKOUT THREAT DRAW IRE OVER RENEWABLE ENERGY TRANSITION

Many parts of the state saw temperatures rise over 100 degrees Fahrenheit on Sunday, as a record-shattering high of 121 degrees was recorded in the nearby Woodland Hills neighborhood of the San Fernando Valley.

The exceptionally hot temperatures were driving the highest power use of the year, and transmission losses because of the wildfires have cut into supplies.

The managers of California's power grid are warning there could be rolling blackouts if customers don't conserve energy. (AP Photo/Richard Vogel, File)

"We have very severe conditions on the grid," ISO’s vice president for operations, Eric Schmitt, told reporters.

Schmitt described Sunday as "our most challenging day of the year."

In this Aug. 18, 2017, file photo, electrical power flow, and conditions are monitored at the California Independent System Operator (California ISO) grid control center in Folsom, Calif. (AP Photo/Rich Pedroncelli, File)

At about 7 p.m., the ISO declared an emergency and said power outages were imminent because a transmission line carrying power from Oregon to California and another in-state power plant went offline unexpectedly. The cause of the outages is unknown at this time, the agency said.

But about 8:30 p.m., the agency issued a tweet calling off the emergency “thanks to conservation of Californians!" It said no power outages were ordered by operators of the grid.

CALIFORNIA HEAT WAVE LEAVES THREAT OF ROLLING BLACKOUTS FOR MILLIONS AS GOV. NEWSOM CALLS FOR PROBE

One of the current wildfires burning in the state, the Creek Fire, has forced the closure of a 915-megawatt hydropower station, “further constraining grid resources," Gov. Gavin Newsom’s office told the Sacramento Bee.

The Creek Fire burns in the Sierra National Forest, Sunday, Sept. 6, 2020, near Big Creek, Calif. (AP Photo/Marcio Jose Sanchez)

Another statewide Flex Alert is in effect on Monday from 3 p.m. to 9 p.m., where residents are urged to postpone using large appliances and raise their thermostats.

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The state's largest utility, Pacific Gas & Electric, warned customers on Sunday that it might cut power on Monday and Tuesday because of expected high winds and heat that could create an even greater fire danger.

The Public Safety Power Shutoff (PSPS) event starting Monday night could impact 103,000 customers in portions of 17 counties in the Sierra foothills and North Bay.

"Due to forecasted extreme weather conditions, PG&E is considering proactively turning off power for safety," the company said in a statement. "Windy conditions, like those being forecast, increase the potential for damage and hazards to the electric infrastructure, which could cause sparks if lines are energized."

Some of the state’s largest and deadliest fires in recent years have been sparked by downed power lines and other utility equipment.

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As of Sunday night, Cal Fire said 14,800 firefighters were battling 23 major fires across the state.

California has seen 900 wildfires since Aug. 15, many of them started by an intense series of thousands of lightning strikes.

A group sits inside a circle designed to encourage social distancing at Dolores Park during the coronavirus outbreak in San Francisco, Sunday, Sept. 6, 2020. (AP Photo/Jeff Chiu)

The blazes have burned more than 1.5 million acres (2,343 square miles). There have been eight fire deaths and nearly 3,300 structures destroyed.

The Associated Press contributed to this report.