Extreme Heat Hits the US During World Cup and July Fourth

A dangerous heat wave swept across large parts of the United States on July 1, bringing scorching temperatures and thick humidity to millions of people. The timing was especially difficult, as the country was co-hosting the FIFA World Cup and getting ready to celebrate the 250th anniversary of American independence on July 4. About 46 million people were under heat alerts, meaning weather officials had warned them to take extra care. Cities from the Midwest to the East Coast felt the effects, with Washington, D.C., New York, and Chicago among the hardest hit.

Scientists call this kind of event a "heat dome." It happens when a high-pressure system acts like a lid on a pot, trapping hot air close to the ground. The heat dome had been sitting over the Midwest and the South, and it was slowly moving east toward more crowded cities. New York Mayor Zohran Mamdani warned residents in a video message, saying, "We are entering what could be the most extreme heat wave this city has seen in over a decade." He urged people to stay safe whether they were watching World Cup soccer, celebrating the Fourth of July, or just going about their day.

New York City took several steps to help people stay cool and safe. The city opened hundreds of public buildings as cooling centers where anyone could go to escape the heat. It also extended pool hours, sent volunteers to check on elderly and sick residents, and set up "pop-up" cooling stations with misting fans and wet towels. In Chicago, the electric company ComEd said the energy grid was under "critical strain" because so many people were running their air conditioners at the same time. The company asked residents to set their thermostats a little higher and to wait until after 8 p.m. to run dishwashers, do laundry, or charge electric vehicles.

Experts say heat waves like this one are becoming more common, and that climate change is a big reason why. Global average surface temperatures have risen about 2.5 degrees Fahrenheit above what they were before humans began burning large amounts of fossil fuels like coal, oil, and gas. More frequent, longer-lasting, and more intense heat waves are one of the clearest signs of this change. Europe has also been hit hard by extreme heat in recent years, showing that this is a worldwide problem and not just a US issue.

Washington, D.C., was expected to face some of the worst conditions. Forecasters predicted three straight days above 38 degrees Celsius starting July 2, with July 3 possibly hitting 40 degrees Celsius. If those forecasts came true, the city would break its daily heat record three days in a row. Washington's all-time high temperature is 41 degrees Celsius, and even that long-standing record was considered at risk.

The Fourth of July holiday added extra challenges on top of the heat. Fireworks, which are a beloved tradition for the holiday, actually release tiny harmful particles into the air that can cause breathing problems. When heat and smoke from fireworks combine, the health risks become even greater. Doctors and health officials urged people to stay hydrated, limit time outdoors, and take breaks in air-conditioned spaces throughout the day.

Visitors to Washington shared their own ways of coping with the extreme weather. Jaden Martin, a 22-year-old marketing worker from Arizona, said he was used to dry desert heat but found the humidity much harder to handle. "We're good with the heat, but the humidity is a different beast," he said while walking his rental bike along the National Mall. Teachers Cecile Hansen and Peter Helmkamp, visiting from Miami, Florida, recommended fans, sunblock, visors, and stepping into air-conditioned cafes every 20 minutes. Hansen, 50, also suggested freezing a water bottle before heading outside to help stay cool throughout the day.

The World Cup added another layer of difficulty to the heat emergency. On July 4, Paraguay and France were scheduled to play in Philadelphia in an open-air stadium, where temperatures were forecast to reach 39 degrees Celsius. Unlike some World Cup venues, Philadelphia's stadium has no air conditioning, meaning players and fans alike would face the full force of the heat. To protect players, this edition of the World Cup required a three-minute hydration break every half of each match, giving athletes a chance to drink water and cool down before continuing play.