(Bloomberg) -- Most of the US is facing elevated blackout risks this summer in the event of widespread extreme heat as the power network serving roughly 400 million people grows increasingly fragile. 

The US West, Midwest, Texas, Southeast, New England as well as Ontario in Canada “may experience shortfalls” of power amid temperatures spikes in coming months, according to a warning from the North American Electric Reliability Corp.

The warning, which took the form of a media notice issued late Wednesday, is more widespread than the group’s 2022 summer assessment because this year’s includes the US Southeast. NERC, as the non-profit that sets reliability standards for US and Canadian grids is known, is scheduled to release it’s full seasonal assessment on May 17.

Providing power to homes, businesses and institutions is growing more challenging in nations such as the US coping with aging electricity networks, the accelerating shift to renewables, and more severe weather.

Read More: Why US Power Substations Are Such Vulnerable Targets: QuickTake

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