(NewsNation) — As millions of Americans face scorching summer heat, some states have seen demand for electricity surge to record highs but so far, power grids are holding up.

Last week, more than 180 million people in the U.S. were under a heat advisory as temperatures climbed into the mid-90s across the country. It was a sweltering end to the hottest month ever recorded on Earth.

The heat wave pushed people indoors to air conditioning, which placed additional strain on electrical grids.

NewsNation spoke with two experts about the unique challenges power grids face during the summer and learned which weather conditions pose the highest risks.

Why are power grids vulnerable during the summer?

Historically, residential electricity consumption tends to be highest in the summer when Americans crank the air conditioning to cool off. This is especially true in southern states where it’s typically warmer.

Higher demand puts more pressure on power grids but the summer presents other challenges as well.

Unlike the winter months, when electricity consumption fluctuates more consistently throughout the day, summer demand ramps up rapidly as it gets warmer, peaking in the early evening. In other words, a lot of people want electricity at the exact same time — demand isn’t just higher, it surges.

And American households aren’t the only ones who need air conditioning. Movie theaters and retail stores have to keep their customers cool.

Ed Hirs, an energy fellow at the University of Houston, said the extreme temperatures in places like Texas and Arizona can also burden physical infrastructure.

“The high heat that we’ve experienced across the southwest of the United States has also strained the equipment,” he said.

Hirs pointed out that summer is typically construction season, which means the industrial sector also draws more electricity.

Can weather cause blackouts?

So far, America’s power grids have avoided rolling blackouts this summer but widespread extreme weather could present challenges.

In May, the North American Reliability Corp. (NERC), which oversees the nation’s grid reliability, put two-thirds of the country — including all of the American West and Texas — at “elevated risk” of electricity shortfalls during periods of “more extreme summer conditions.”

Wildfires present risks, particularly in the West. Other regions, that rely on wind and solar, could face issues on hot, cloudy days.

The interconnectedness of the nation’s power grids helps mediate some of those risks because regional grids can shift excess capacity to areas that need it during peak hours.

That works most of the time but when there’s no excess capacity to spare, there can be problems.

In August 2020, California’s three largest utility companies were forced to shut off electricity for hundreds of thousands of homes after the state’s power grid was overwhelmed.

“[California] realized that they couldn’t rely on their neighbors to draw in additional power because the heat cell that settled over California also settled over Nevada, Arizona, Washington, Oregon,” Hirs said.

Where is electricity demand at an all-time high?

States in the southwest have been hit especially hard by the heat. Residents of Phoenix, Arizona recently endured a record-breaking 31 consecutive days of temperatures above 110 degrees.

Arizona Public Service, the largest electric utility in the state, reported record levels of energy consumption during multiple days last month.

In Texas, Austin is currently experiencing the longest stretch of triple-digit heat in recorded history.

The Lone Star State saw record-breaking demand for electricity in July. But so far, Texas has avoided an energy crisis like it saw in February 2021, when a spate of winter storms left millions of people without power in below-freezing temperatures.

Are other states seeing record levels of electricity consumption?

For now, Arizona and Texas appear to be outliers.

In many parts of the country, demand for electricity has remained within the typical range, according to a recent analysis by Lucas Davis, a professor of economics at the Haas School of Business at UC Berkeley.

That’s because a lot of highly populated regions have been spared from the scorching temperatures.

“There’s a really strong correlation between high temperatures and electricity consumption,” Davis said. “The places that have gotten the hottest, you’re seeing records.”

Davis, who is also a faculty affiliate at the Energy Institute at Haas, looked at the last 14 years of daily peak electricity consumption in several U.S. markets and found that 2023 levels have been similar to other years, with Texas as the exception.

Most of California, for example, hasn’t had record-breaking heat this summer like in previous years where capacity was an issue.

What makes Texas unique?

Texas is the only state with its own electrical grid, which means it can’t draw from other places when demand surges.

At the same time, the state has seen a flood of new residents in recent years. To meet the rising demand, Texas invested heavily in wind and solar which made the grid more reliant on renewable energy sources, Hirs said.

That means a hot, cloudy, windless day could present energy supply issues. The NERC said as much in its May assessment when it warned that Texas may not be able to meet demand “during an extreme heat-wave that is accompanied by low winds.”

“The portfolio of coal, natural gas and nuclear power plants did not grow at all [from 2010 to 2021] and so the reliability aspects of the [Texas] grid diminished over time,” Hirs noted.

He said the lack of investment has led to a higher percentage of unplanned outages at coal and natural gas plants this year.

For now, renewable energy sources have helped meet the state’s needs and are performing “well above expectations,” Hirs added. Non-fossil fuel resources contributed as much as 55% of total generation on peak days in June, according to the U.S. Energy Information Administration.

The state hasn’t had rolling outages due to hot weather since 2006, the Associated Press reported.

What about California?

State regulators said the blackouts that occurred in 2020 are unlikely to happen this summer, in part, thanks to a wet winter that filled the state’s reservoirs enough to restart hydroelectric power plants.

That rainfall has been good news for the entire region, including Oregon and Washinton, Davis said.

“Hydro is the perfect substitute to those renewables on those days that don’t have sun and wind,” he explained.

Despite the promising outlook, Davis isn’t declaring victory just yet.

“We’ve still got August and September, so we’ll see,” he said.