In a matter of weeks, California has been hit with two record-breaking heat waves, hundreds of blazes, freak lightning storms and dangerously poor air quality, and now unusually strong winds are threatening to knock down power lines and ignite more wildfires.

That’s prompting the state’s largest utility to impose power cuts for more than 500,000 people, and with dangerous conditions stretching across the West, Portland General Electric Co. has also switched off power to some Oregon customers.

The shutoffs that PG&E Corp. began late Monday are the latest blow for the disaster-weary California, where climate change is making weather ever more extreme. Temperatures have soared to records from Napa to Los Angeles. Wildfires have torched more than 2 million acres, the most in records stretching back three decades. Hundreds of thousands of people may go dark for days while trapped indoors due to wildfire smoke and Covid-19 outbreaks.

Officials are responding with equally extreme measures. In August, California carried out its first rotating blackouts since the 2001 energy crisis, drawing the ire of millions who went powerless amid extreme temperatures. The Trump administration declared a power emergency, allowing power plants to run at full bore, regardless of environmental limits. The shutoffs that began late Monday are a fairly new and controversial practice, and their use last year triggered investigations while utilities defended them as necessary in the face of increasingly wild weather.

Now, as a second round of ferocious temperatures abates, so-called Diablo winds sweeping in have set the conditions for even more fires. PG&E, which filed for bankruptcy last year after its equipment sparked deadly wildfires, warned the precautionary shutoffs could impact portions of 22 counties from late Monday through Wednesday, including in the Sierra foothills and North Bay.

“Unfortunately, the continued hot and dry weather is going to continue to dry out vegetation across California — and make that vegetation even more susceptible to new admissions and large fires,” Scott Strenfel, a PG&E meteorologist, said during a public briefing late Monday.

PG&E, which emerged from Chapter 11 in July after agreeing to pay $25.5 billion to settle wildfire lawsuits, said preemptive shutoffs that started late Monday could leave about 172,000 homes and businesses in the dark. That could impact up to 516,000 people, based on the size of the average California household.

Shutoffs were expected to affect about 104,000 customers starting from 9 p.m. local time Monday, with the remainder going down in two phases Tuesday. Some customers may not have power restored until 9 p.m. Wednesday, according to an announcement Tuesday morning.

PG&E also plans to turn off about 100 transmission lines and 145 distribution lines, it said during the briefing.

In Oregon, high winds have knocked out electricity to about 80,000 Portland General customers, and for the first time the company intentionally cut power to about 5,000 homes and businesses near Mt. Hood.

The U.S. Forest Service said in a statement Monday that most of California “remains under the threat of unprecedented and dangerous fire conditions.” It has temporarily closed eight national forests, including Sierra National Forest.

“Existing fires are displaying extreme fire behavior, new fire starts are likely, weather conditions are worsening, and we simply do not have enough resources to fully fight and contain every fire,” Randy Moore, regional forester for the forest service’s Pacific Southwest Region, said in the statement.

California narrowly escaped rotating blackouts Saturday and Sunday, as temperatures soared past 100 degrees Fahrenheit (38 degrees Celsius) in much of the state, squeezing the power grid to its brink. The fires only made things worse, taking down power plants and transmission lines, cutting power to 70,000 homes and businesses.

While temperatures were lower Monday in some areas, officials said they were still concerned about getting through the afternoon, in part because of the fires. But in a tweet Monday night, the grid operator said it wouldn’t order power outages.

The heat is poised to ebb only slightly Tuesday. Sacramento is forecast to hit 97. Oakland will be 91. And Los Angeles will be 87.

The latest blazes are already wreaking havoc on the grid. The Creek Fire in the Sierra Nevada Mountains, which has scorched more than 78,000 acres, knocked out transmission from a hydro plant on Saturday.

September and October typically mark the peak of California’s fire season, when plants have been sapped of moisture by the state’s dry summer. Rains most often return in October or November.

Last year, when California’s utilities first began carrying out widespread blackouts like this, some homes and businesses were left in the dark for days. That drew outrage from state and local officials, triggered investigations and prompted PG&E to reassess the scope of future shutoffs. The company has taken steps to limit the size and duration of outages, including putting wires underground in some locations.