(NewsNation) — A new report on the nation’s power grid has issued a stark warning about the country’s ability to keep the U.S. cool.

As summer heats up, it takes more and more power to cool down and to keep millions of Americans from sitting in the dark.

Electricity is a thing many Americans take for granted, at least until it’s gone. Rolling blackouts and power outages can affect people’s health, safety and overall quality of life.

According to a new report from the North American Electric Reliability Corporation, the hotter it gets, the more dire the outlook becomes for the nation’s unstable power grids.

America’s high energy demand has the potential to cause the lights to go out for a staggering two-thirds of the country, according to the report’s findings.

“The risk of energy shortfalls is increasing and spreading to more areas of the country,” said NERC President and CEO Jim Robb. “This is due to areas of extreme weather we’ve had, with heat events impacting the West and widespread severe cold events impacting eastern portions of the U.S.”

The combination of extreme weather, including hurricanes, wildfires and storms, coupled with slow development of the nation’s energy infrastructure, could cripple an already taxed system, one that, according to NERC, is already close to the edge.

Sen. Joe Manchin, D-W.V., called the latest assessment frightening.

The Senate Energy and Natural Resources Committee met recently to discuss the reliability of the power grid and the nation’s elevated risks for blackouts spreading from Texas to California, the Midwest and New England.

“When electricity is unreliable, the potential consequences are nothing short of catastrophic, including the loss of human life,” Manchin said.

With tens of millions of Americans at risk, cities are desperate for ways to prevent blackouts.

In recent years, California, the nation’s most populous state, turned to wind, solar and water power. But during hot summers, the state’s 39 million residents suffer through rolling blackouts.

In Texas, where the state electric grid is not connected to the rest of the U.S., the power grid failure of 2021 left more than 200 people dead. Now the push is on for renewable energy as the state’s utility commission warns its main power grid is once again at risk of failure under high demand.

New Englanders have increased the use of solar power to relieve the strain on their electric grid, but in times of extreme heat, residents and businesses could be asked to voluntarily conserve energy or face rolling blackouts.

In Phoenix, America’s hottest big city, a deadly five-day heat wave with temperatures ranging from 90 to 113 degrees could result in power outages and a lack of air conditioning, which, according to the scientific journal Environmental Sciences and Technology, could severely affect more than half a million residents.

“Most people studying the energy system say you need to keep balance between affordability, reliability and climate. If one gets out of whack, bad things start to happen,” Robb said.