Searing heat threatens grids and health over nearly half the US

Brian K. Sullivan, Bloomberg News on Jul 28, 2025

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Nearly half the U.S. will wilt under hot, sticky conditions through the bulk of the week as temperatures and humidity soar from Chicago to New York City and New Orleans, boosting power demand and raising health risks.

Heat advisories and extreme heat warnings stretch from Nebraska to Long Island and from New Hampshire to northeast Texas.

Monday’s high in Central Park is forecast to reach 94F (34C), but with humidity it will feel closer to 100F or more. Chicago will likely reach 91F and feel closer to 102F, the National Weather Service said.

A weather front dropping down from the north will start to bring relief through the week to most areas except the deep South, which will linger with hot, sticky conditions for days to come.

“We just have to get through the next few days, especially for the Northeast,” said David Roth, a senior branch forecaster at the U.S. Weather Prediction Center.

The high temperatures have raised alarms for utilities and grid operators from the central U.S. to the Atlantic as people turn to air conditioning. The heat has also slowed rail traffic as trains need to move carefully across heated tracks.

PJM Interconnection LLC, a grid operator that moves electricity across 13 states and the District of Columbia, issued hot weather alerts for its Mid-Atlantic and Southern regions Sunday and for its entire operating area on Monday. It also called on power plants to be ready for service and that it may curtail exports to neighboring grids if demand rises.

In addition to stressing infrastructure, people’s health is at risk. From 1979 to 2022, more than 14,000 Americans died from heat-related causes, according to the U.S. Environmental Protection Agency.

Only a few records have been set so far, including an all-time high of 100F in Tampa on Sunday, the weather service said. Usually breezes off the Gulf keep temperatures in the Florida city peaking in the 90s, but on Sunday that didn’t happen, said Roth.

There will also be a fair amount of weather whiplash, particularly in New England where temperatures were 65F early Monday in Boston and are forecast to reach nearly 90F later in the day and 98F on Tuesday.

New York will continue to swelter through late Wednesday, the weather service said in its advisory. Roth said the advisories may drop in other places with the setting sun, though they could return the next day until the front finally pushes through. That’s because overnight lows won’t get high enough in those areas to sustain the bulletins.

—With assistance from Naureen S. Malik.