(Bloomberg) -- California braced for another day of blistering weather and potential blackouts as officials called for power conservation amid searing heat stretching electricity supplies across western states.

Grid officials kept the lights on late Thursday but warn Friday evening will be another close call, urging consumers to keep curbing their power use as solar power generation fades with sunset.

The most populous state is already flirting with a repeat of historic rotating outages that darkened some of the largest and most productive U.S. cities in August. The threat comes even before the solstice marks the official start of summer on Sunday, signaling that the power crunch may intensify in coming months. It also underscores the magnitude of challenges for officials struggling to address growing heat, drought and wildfire threats linked to climate change.

“We are being foretold of the ghost of summer yet to come,” said Gary Ackerman, an independent energy consultant who founded the Western Power Trading Forum. “It’s not just whether there is enough water -- there’s not -- and whether there’s enough power or whether there are wildfires. If you have a combination of all those things you have an Armageddon on your hands.”

The pressure on energy resources is likely to continue into this weekend, with the National Weather Service warning of “dangerously hot conditions” through Saturday evening.

Temperatures have topped 100 degrees Fahrenheit (38 degrees Celsius) from the southeastern desert to near Oregon, while sparing big coastal cities. Sacramento hit 110 degrees Thursday, a record for the date, while Death Valley National Park hit 128 degrees, eclipsing the date’s all-time high.

California and the Southwest will swelter for a few more days before cooling filters in through the region by Monday. California’s Central Valley “will get quite a bit more relief” with temperatures retreating to the 90s, said William Churchill, a forecaster with the U.S. Weather Prediction Center.

Much of California has been mired in extreme drought, and parched vegetation is poised to burn after a dry winter. The lack of seasonal rains also has reduced hydropower generation, adding to supply woes just as neighboring states like Arizona and Nevada also face rising power demand.

“Summer hit us a little earlier than expected,” Federal Energy Regulatory Commission Chairman Richard Glick told reporters Thursday. “We are seeing extreme conditions happen earlier. We are seeing them happen with more ferocity than we have, clearly related to climate change.”

Blackouts were averted Thursday mainly by conservation, with consumers asked to avoid unnecessary evening use. The California Independent System Operator renewed those requests for Friday to help alleviate the stress on the electric grid that it oversees.

Governor Gavin Newsom also freed up additional energy supplies with an emergency declaration, while grid officials were also able to import more power from neighboring utilities. Although the heat has engulfed most of the Southwest, it hasn’t stretched north to Portland, Oregon, or Seattle, making it easier for California to import electricity from the Pacific Northwest.

PG&E Corp., California’s biggest utility, said a blackout Thursday night would have affected 121,000 customers for an hour or two.

State officials have worked in recent months to avoid a replay of August’s outages, the first in two decades. They delayed planned retirements of old, gas-fired power plants and tweaked electricity market rules to encourage imports when demand soars. Power companies also started installing large batteries to store solar power during the day and feed it back onto the grid in the evening.

The state estimates those batteries will boost capacity by about 2,000 megawatts -- roughly equivalent to the output of two nuclear reactors -- by August, and some are already running. By contrast, grid officials forecast demand Friday will peak at more than 41,000 megawatts.

Meanwhile, traders betting this week on electricity shortages across the western U.S. drove a key spread between prices in Arizona and those in the Los Angeles area to the widest ever.

Power regularly travels between Southern California, the Pacific Northwest and the Southwest, depending on regional needs. But the record spread highlights how climate change has brought about such extreme weather for all three regions that there isn’t always enough power to go around.

California officials have been bracing for a difficult season after winter brought few storms, the second year in a row that the rainy season fizzled. And the ensuing drought couldn’t come at a worse time for Newsom, who faces a likely recall election this fall.

He’s trying to avoid another devastating fire season and the heat-triggered blackouts that left more than a million Californians in the dark while stuck home amid lockdowns. The current heat comes as the state reopens this week, lifting most of pandemic restrictions.

“My mind is immediately focused on issues of energy security, immediately focused on issues of wildfire season,” Newsom said Wednesday at a press conference.

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