The United States and Canada are enduring a prolonged severe heatwave, pushing the heat index up to approximately 46.1 degrees Celsius. Over 250 million people are at risk, impacting plans for the US's 250th Independence Day celebrations and potentially affecting World Cup matches. This is attributed to global warming causing unusually rapid temperature increases, similar to recent events in Europe.
The US National Weather Service issued an extreme heat warning covering around 120 million people before the heat mass expands widely from Thursday onward. Approximately 250 million people—nearly the entire country—ranging from the Midwest and Mississippi River Valley to the East Coast will face dangerous weather conditions.
The "heat dome" phenomenon, caused by a high-pressure system trapping heat and humidity in the atmosphere, has raised normal temperatures to 35–40.5 degrees Celsius. Combined with high humidity, the "heat index" or perceived temperature reaches 37.8–46.1 degrees Celsius, expected to break daily high-temperature records in many areas.
This heat crisis coincides with the extended Independence Day holiday marking the US's 250th anniversary, during which parades, outdoor concerts, and annual boat cruises are scheduled. Major cities such as New York, Boston, and Philadelphia have issued warnings to beware of the dangers.
New York City Mayor Eric Adams declared an emergency heat response plan, opening hundreds of "cooling centers" across the city, including at the Javits Center exhibition hall. Mobile vans will distribute drinking water, electrolytes, and sunscreen to disabled individuals and the homeless. Authorities have also requested businesses in Times Square to dim billboard lights and urged stores to keep air conditioning at no less than 25.5 degrees Celsius to prevent power grid failures.
This scorching weather also raises concerns for the ongoing World Cup. The World Players' Association reported that the heat index in some matches has exceeded safe limits for athletes. Texas recorded the nation's highest temperatures, directly affecting fans traveling to and from air-conditioned stadiums in Houston and Arlington.
In Atlanta, Georgia, fans and players faced extreme heat during the match between England and the Democratic Republic of Congo. Meanwhile, Toronto, Canada, has issued an orange alert in Ontario. On Thursday, Toronto is set to host a World Cup match, with temperatures expected to reach 35–37 degrees Celsius.
Climate experts note that large cities with concrete, asphalt, and steel structures absorb and retain heat, causing residents to feel hotter than the temperatures reported on their phones.
Residents across affected areas are adapting but feeling widespread impacts. Dana Robles, a Brownsville, Texas resident, expressed concern that this month's electric bill could exceed $300 (about 10,000 baht), which is one-third of her rent. She fears that power outages would spoil all refrigerated food. Amy Kaspar, a real estate investor in Chicago, compared the weather, saying, "With the wind, it feels like we’re constantly standing behind a bus’s exhaust pipe."
Scientists from Columbia University's climate research institute confirm that the current rapid and intense heatwaves are the clearest measurable effects of human-induced climate change, similar to recent events in Western Europe. Without global warming, such extreme weather events would be almost impossible.