Extreme Heat Warning for New York City through the July 4th weekend | Live updates

Con Edison reduced voltage by 8% in the northwest section of the Bronx and in the northern tip of Manhattan to protect equipment and maintain service as repairs are made amid the extreme heat.

The affected area in the Bronx includes 39,600 customers and is bounded by the Westchester County line on the north, the Harlem River on the south, the Hudson River on the west, Sedgwick Avenue and the Bronx River on the east. It includes parts, or all, of these neighborhoods: Riverdale, Marble Hill, Kingsbridge, and Van Cortlandt Park.

The affected area in Manhattan is bounded by West 155th Street on the south and stretches to the Harlem River on the north. It is bounded by the Hudson River on the west and the Harlem River on the east. The area includes 75,200 customers in the Inwood, Hudson Heights and Washington Heights neighborhoods.

As oppressive heat settled in on Wednesday, some diehard soccer fans ventured out to watch the big World Cup match.

New York is sizzling in this historic heatwave, but it's a special summer with all kinds of fans visiting for the World Cup.

The sunset did not provide much relief -- it was still hot and sticky and there was not much of a breeze off the Hudson either.

Sonia Rincon has more on how World Cup fans tried to beat the heat.

You could call this a warmup for the 4th, when all eyes will be on the fireworks over both rivers.

Mayor Zohran Mamdani announced earlier Wednesday expanded measures to help protect New Yorkers from the heat, like extended pool hours and cooling vans that can help or check on anyone suffering.

In the city, the heat and holidays traditionally mean an exodus of locals -- but others will be arriving for a taste of the Big Apple as it bakes.

In Hamptonburgh, New York, air conditioning failed on a bus carrying Junior ROTC cadets, resulting in multiple heat-related illnesses, Orange County authorities said.

The cadets are all under the age of 18.

Some cadets were taken to hospitals as a precaution.

With 160 million people in 30 states under alert for extreme temperatures, the U.S. Department of Energy has declared an emergency as a heat wave bears down on a huge part of the nation's electrical grid.

U.S. Secretary of Energy Chris Wright issued an Energy Emergency Alert, directing officials of the biggest electrical grid, PJM Interconnections in the Mid-Atlantic region, to take action to prevent blackouts and ensure essential operations like hospitals are fully functioning during the heat wave.

The dangerous heat wave is bringing prolonged extreme heat along the East Coast, the Midwest and the South.

The New York Independent System Operator (NYISO), which operates the state's electrical grid, said it is also expecting electricity demand to approach record highs over the next few days.

Read more from ABC News.