The first major heat wave to hit the United States this summer rolled in just as the season was getting started. Numerous records were shattered, with triple-digit temperatures as far north as New Hampshire.

What's happening?

Searing conditions swept all the way into New England during a late-June heat wave. Several spots in the Northeast hit highs of 100 degrees or hotter during the scorching streak from June 23 to June 25, including Concord, New Hampshire (100), Wilmington, Delaware (101), Boston, Massachusetts (102), and Newark, New Jersey (103).

According to a report from the Northeast Regional Climate Center, at least four cities in the assessed area not only set historic highs but hit 100 degrees or more for the first time on record during the month of June.

John F. Kennedy Airport hit 102 degrees on both June 24 and June 25. It was the first time the airport had ever hit 100 degrees.

"It feels like an armpit out here," Marvin Martinez, a personal trainer who endured the heat in New York, told CBS News.

At the peak of the streak, over 107 million people across portions of at least 26 states were under heat advisories, while nearly 26 million people in parts of at least nine states saw extreme heat warnings.

Why is the first heat wave important?

This extreme heat and humidity in June wasn't just uncomfortable — for some, it was deadly.

Two people, including a 51-year-old postal employee, died in the Dallas region at the onset of a relentless heat wave that persisted for days.

In Mansfield, Ohio, a 5-year-old boy died after being left inside a car during this first major bout of extreme heat.

A joint report released by World Weather Attribution, the Red Cross Red Crescent Climate Centre, and Climate Central investigated the connection between climate change and extreme heat between May 1, 2024, and May 1, 2025. The study's revelations about the growing severity of scorching temperatures are deeply concerning.

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Almost half the global population endured 30 or more days of extreme heat during the timeframe explored in the study, with extreme heat defined as "hotter than 90% of temperatures observed in their local area over the 1991-2020 period." An estimated 4 billion people were affected.

"One of the most consistent climate attribution science findings is that every heat wave today is made more likely, more intense, and longer-lasting due to humans burning fossil fuels," the study concluded. "In the last few years, researchers have identified many deadly extreme heat events that would have been virtually impossible without human-induced climate change."

What's being done about worsening heat waves?

Periods of hotter weather have long been a part of life on Earth, but they're being supercharged now by the heat-trapping pollution produced by human activities, such as driving gas-powered cars and burning fossil fuels to generate electricity. Cooling our overheating planet will require a massive shift away from our reliance on dirty energy.

The good news is that we already know alternatives like geothermal and solar energy can help curb harmful carbon pollution. And some governments are collaborating to enable the mass transition to renewable systems, while plenty of individuals are coming together to take on the switch themselves — turning to electric vehicles, public transportation, sustainable consumer practices, and solar panels.

Connecting those entities — communities and municipalities — through local efforts and public-private partnerships may prove vital in spreading awareness of critical climate issues and developing pro-climate policies to mitigate the heat waves to come.

In the meantime, such connections can also help protect the public from heat-related illness, as individuals and agencies join forces to communicate health guidelines, check in on vulnerable neighbors, and open accessible cooling centers.

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