The sun sets through smoke created by the Ranch Fire on Aug. 13, 2020, in Azusa, Calif. A heat wave has prompted electrical providers to issue the first rolling blackouts in the state since 2001.

The sun sets through smoke created by the Ranch Fire on Aug. 13, 2020, in Azusa, Calif. A heat wave has prompted electrical providers to issue the first rolling blackouts in the state since 2001. / AP

California electrical providers instituted rolling blackouts Friday night – the first since 2001–as an intense and prolonged heat wave settled over much of the Western U.S.

Hundreds of thousands of people are believed to have experienced brief power outages through the evening, after the body that manages most of the state's electrical utilities declared a Stage 3 emergency to help reduce stress on the larger grid.

Electrical demand surged through the day as temperatures topped the triple digits in many parts of the state and people cranked up fans and air conditioning units to try and stay cool.

The emergency order was rescinded before midnight and power was fully restored to all affected households, the California Independent System Operator said in a tweet.

Still, demand for electricity is expected to remain high through the weekend and well into next week. The heat wave blanketing much of California and other parts of the Western U.S. is expected to persist until at least Thursday, with many places expected to reach record high maximum and minimum temperatures, according to the National Weather Service. The forecast raises questions about future electrical demand and the potential for more blackouts.

Daniel Swain, a climate scientist at UCLA, says the heat wave could be the worst in more than a decade.

Extreme heat is a silent killer, responsible for more deaths than any other natural disaster. The Centers for Disease Control and Prevention estimates that heat kills more than 600 people in the U.S. every year.

However, a recent study by researchers at Boston University and the University of British Columbia suggests the number may actually be far higher — possibly as high as 5,600 annually — with even moderate heat waves increasing the number of deaths.

Climate change is making heat waves more frequent and more intense in the Western U.S., and it's doing the same to wildfires.

Fire season is just heating up in California, with more than dozen blazes burning through the state. The heat wave won't help firefighting efforts and there are concerns it could dry out vegetation in other parts of the West, setting the stage for future fires. Fortunately, strong winds – a chief driver of California's recent deadly fires – are not forecast in the coming week. But that also means that unhealthy air and higher-than-normal humidity are likely to remain in parts of the state.

Efforts to protect people from the combination of those factors as well as blistering temperatures are being complicated by the ongoing pandemic. Health officials are urging people to stay at home and, in some parts of the country, communities have closed cooling centers to try and prevent the spread of COVID-19. That's not the case in most of California, where state and local officials have activated cooling centers to help people in need.

Many low-income families in Los Angeles lack the resources to cool their own homes, according to a recent study by researchers at the University of Southern California. In some cases, they don't have access to air conditioning. In others, they can't afford to pay for the electricity to run it.

Hundreds of thousands of Californians remain out of work because of the coronavirus pandemic, amplifying economic insecurity for families across the state.

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