Blackouts are likely this summer in the United States, according to the North American Electric Reliability Corp.

The NERC warning came late on Wednesday, calling for "shortfalls" in power supplies to the U.S. West, Midwest, Texas, Southeast, New England โ€” as well as Ontario โ€” as temperatures rise.

Last year, the warnings of power blackouts were less severe, in part because they didn't include the U.S. Southeast.

"A combination of extreme peak demand, low wind, and high outage rates from thermal generators could require system operators to use emergency procedures, up to and including temporary manual load shedding," the North American Electric Reliability Corporation said in its Summer Reliability Assessment report released last year in the run-up to summer.

Texas, in particular saw a major heat wave last summer that strained the state's electric grid, triggering a call from the state's electricity regulator, ERCOT, to consumers to conserve energy. At the time, wind turbines in Texas were operating at just 8% of their capacity.

This year's full summer assessment will be published next week.

The U.S. power grid is faced with other challenges that go beyond power disruptions due to extreme temperatures. The number of attacks on the U.S. power grid infrastructure with gunfire or vandalism grew last year, and it is likely to rise this year, too, according to a confidential NERC analysis seen by the Wall Street Journal earlier this year.

Last year, the number of physical attacks - including intrusion, vandalism, and gunfire - jumped by 71% from 2021, according to the Electricity Information Sharing and Analysis Center, or E-ISAC, a division of North American Electric Reliability Corporation (NERC).