NEW YORK – A massive heat dome that sparked the first major heat wave of the summer brought record-breaking temperatures to cities from the Midwest to the Northeast this week, but some much-needed relief from the extreme weather is on the horizon.

Officials across the eastern half of the U.S. urged people to prepare and take precautions to prevent heat-related illnesses as temperatures skyrocketed. Still, it wasn’t only the heat that proved to be dangerous.

On Monday, a group of 20 people, including children, were cooling off in a South Carolina lake when they were suddenly struck by lightning as a thunderstorm swept through Lexington. 

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On Monday, 30 cities across the eastern half of the U.S. broke or tied century-old records and 11 cities on Tuesday did the same. Among the most notable records that were broken on Tuesday include Islip, New York, which reached 100 degrees. That makes it the third-hottest day on record for that location.

Plattsburgh, New York, tied its old record of 101 degrees, and Newark, New Jersey, hit 103 degrees, breaking its daily record and tying its monthly record. 

Boston soared to 102 degrees on Tuesday afternoon, and Philadelphia hit 101 degrees. That’s the first time the city hit 100 degrees since July 18, 2012.

In total, the FOX Forecast Center said temperatures topped 100 degrees in 13 states, while records from North Carolina to Maine fell.

Power grids strained as millions crank up the air conditioners

In the Southeast, the Department of Energy issued an emergency order amid surging power demand to help mitigate the risk of blackouts. The order authorized Duke Energy Carolina to utilize resources to operate at its maximum output levels in the extreme heat. 

“As electricity demand reaches its peak, Americans should not be forced to wonder if their power grid can support their homes and businesses,” U.S. Secretary of Energy Chris Wright said. “Under President Trump’s leadership, the Department of Energy will use all tools available to maintain a reliable, affordable, and secure energy system for the American people. This order ensures Duke Energy Carolinas can supply its customers with consistent and reliable power throughout peak summer demand.”

The emergency order remains in effect through Wednesday.

Power companies across the East Coast were urging customers to conserve energy as temperatures soared, but said they were prepared to respond to any outages.

Con Edison said crews worked around the clock in hot conditions to restore power to customers in the Bronx in New York City and even handed out dry ice to their customers.

Eversource also asked its customers in Massachusetts, Connecticut and New Hampshire to be aware of their energy usage.

“While high electricity usage during a heat wave can put a strain on the electric system, the energy company is prepared to meet the increased demand, and its crews are ready to respond to any outages or issues that may arise,” the company said.

Relief from stifling heat on the way

Heat alerts remain in effect from the Midwest to New England, but many of the Extreme Heat Warnings – the most dire heat alert – have been reduced to a Heat Advisory.

More than 102 million Americans remain under a Heat Advisory, while just over 25 million remain in an Extreme Heat Warning. This includes cities like Wilmington and Raleigh in North Carolina, Richmond in Virginia, and Philadelphia and Pittsburgh.

Washington, D.C., New York City and Boston have been placed under a Heat Advisory.

Temperatures will once again get into the mid- to upper 90s on Wednesday along the Interstate 95 corridor along the East Coast, but relief is on the way.

New York City, for example, has a forecast high temperature of about 96 degrees on Wednesday afternoon, but on Thursday, the forecast high temperature is only expected to be about 80 degrees.

Friday will feel even cooler, with a forecast high of 68 degrees.

In the mid-Atlantic and Southeast, temperatures are expected to remain in the 90s for the rest of the workweek.