A large swath of the United States is facing a heightened risk of blackouts this summer, a perennial danger as electricity use soars and extreme weather tests the nation’s aging power grid, according to the regulatory authority that monitors the electricity system.

The seasonal electricity forecast warns that regional power grids extending from the Upper Midwest south through Texas may lack the power needed to meet all customer needs in the event of prolonged periods of high temperatures.

The shortfall, according to a new report from the North American Electric Reliability Corporation, or NERC, a nonprofit organization dedicated to reducing risks to power networks, is driven in large part by a steep increase in projected electricity demand.

Power demand is sharply up since last summer, increasing at more than double the rate it did between 2023 and 2024.

The U.S. is now projected to need 10 gigawatts more electricity in the upcoming summer season than it did last summer — the equivalent amount of power it takes to keep the lights on in as many as 10 million homes.

The surge in demand is driven by a number of factors, according to earlier data published by federal and state regulators. The proliferation of energy-hungry data centers and manufacturing plants is a key cause. They are consuming energy faster than utilities can bring new power plants online.

Additionally, scorching temperatures drive more air-conditioning use in homes and businesses, creating a major strain on electricity systems.

The NERC report also points to the transition to green sources of energy as a complicating issue. Large amounts of wind and solar power have been added to the grid in the last year, and their inability to feed energy around-the-clock to the aging power network can destabilize it. While a vast expansion of industrial-size batteries to store that energy is helping, there is not yet enough storage to solve the problem.

At the same time, aging gas and coal plants are being retired.

This is an issue for the regional power grid that serves 15 states from North Dakota to Louisiana, where there will be less power available this summer than there was last summer.

“With higher demand and less firm resources,” the NERC report says, that sprawling power grid “is at elevated risk of operating reserve shortfalls during periods of high demand or low resource output.”

While utilities have been rushing to bring new gas plants online, the pace at which they can move is outstripped by surging energy demand. Supply chain delays and transmission bottlenecks have pushed the time it takes to bring a new plant online to three or four years.

Similar issues are plaguing the ability of grid operators to complete basic upgrades to the network of power lines and transformers that are the backbone of the U.S. electricity system.

The report warns of a shortage of “parts, materials and skilled technicians” that is causing delays in maintenance and installation of new transformers.

As large parts of the nation struggle to bring more power online, the report warns, weather forecasters are warning of another hot and dry summer. The last two summers already rank as among the hottest on record. Such weather, NERC writes, “is one of the main drivers of demand and can also lead to forced outages.”