Millions in US sweat out first extreme heat wave of year

A person shields from the sun with an umbrella in New York on June 23, 2025 after an excessive heat warning was issued for the New York City area. The United States is experiencing its first significant heat wave of the year, which began on June 20. [AFP]

A potentially life-threatening heat wave enveloped the eastern third of the United States on Monday impacting nearly 160 million people, with temperatures this week expected to reach 102 degrees Fahrenheit (39 degrees Celsius) in the New York metropolitan area.

The country's first significant scorching heat of the year triggered health warnings as it arrived over the weekend. Dangerously high temperatures are forecast through Wednesday in Washington, Baltimore, Philadelphia, New York City and Boston.

"This extreme heat will not just be uncomfortable and oppressive for New Yorkers," warned Mayor Eric Adams, adding that each year heat claims the lives of 500 people in this city of eight million.

"It's going to be brutal and dangerous if you do not treat it with the understanding that we want you to," he added.

As sweltering heat baked the city, authorities urged seniors, people with health problems and those without air conditioning to stay hydrated and seek help at designated cooling centers such as libraries and recreation facilities.

Heat records tumbled across parts of the US Northeast. In Central Park, known as the lungs of Manhattan, Monday's temperature of 96F (36C) tied a record that has stood since 1888, according to the National Weather Service.

"Extreme Heat Warnings and Heat Advisories across much of the eastern third of the country (are) affecting nearly 160 million people" across at least 29 states, the NWS reported.

"This level of HeatRisk is known for being rare and/or long duration with little to no overnight relief, and affects anyone without effective cooling and/or adequate hydration," the agency warned.

Meteorologists are describing the intensifying weather pattern as a heat dome, a high-pressure system that traps air and leads to steadily rising thermal readings.

Extreme heat is the deadliest weather-related hazard in the United States, leading to more fatalities than natural disasters like hurricanes or tornadoes.

For many in the Big Apple, avoiding work in the searing heat was not an option.

"We have to endure it, because otherwise what are we going to survive on?" Manuel, a manual worker repairing a building facade in New York's Harlem neighborhood, told AFP.

"Sometimes we stop because it's a danger. We don't all have the same energy, but you have to endure," he added.

In the Washington Heights neighborhood, authorities opened several fire hydrants so residents could seek relief with the gushing water.

One of the local heroes was Ronald Marcelin, a 44-year-old air conditioning technician sweating profusely as he repaired a pizzeria's AC unit.

"I'm taking the heat so that everyone else can cool down," Marcelin said with a grin.

Triple digits

The soaring temperatures come just as New Yorkers head to the polls Tuesday -- with a forecast high of 102F (39C)  -- for the Democratic primary that will decide the party's mayoral candidate.

It promises to be a tight race between Andrew Cuomo, who is seeking political resurrection after resigning in disgrace as state governor in 2021, and rising left-wing star Zohran Mamdani.

Over the weekend, Cuomo urged residents to cast their votes even if the temperatures hit triple digits.

In Washington, the heat index -- what the temperature feels like with humidity factored in -- was forecast to soar as high as 110F (43C) on Monday, and the mayor's office urged residents to take advantage of cooling centers and public swimming pools.

Scientists say extreme heat waves are a clear sign of global warming, and they are expected to become more frequent, longer, and more intense.

Fueled by human-caused climate change, 2024 was the warmest year on record globally -- and 2025 is projected to rank among the top three.