A dangerous and prolonged heat wave is settling over the central and eastern United States, placing more than 130 million people under heat alerts and forcing the cancellation of outdoor activities from the Midwest to the Atlantic seaboard. The National Weather Service (NWS) has warned that temperatures will exceed 100°F (38°C) in many areas, with high humidity pushing the heat index as high as 115°F (46°C) in cities including Chicago, Philadelphia, and Washington, D.C. The heat dome is expected to intensify through the week, coinciding with the July 4 holiday and the knockout stage of the FIFA World Cup.

Cooling centres have been activated in Chicago, Flint, and Des Moines, while summer camps, farmers’ markets, and drive-in theatres have been shuttered. In the nation’s capital, the annual Independence Day fireworks display has been delayed until 11 p.m. to accommodate a presidential rally, prompting Mayor Muriel Bowser to urge families to limit outdoor exposure and “get home as soon as the fireworks are over.” Medical authorities in Detroit and New Jersey have cautioned that the combination of extreme daytime heat and overnight lows remaining in the mid-70s will sharply increase the risk of heat-related illness, particularly for the elderly and those without adequate cooling. In the West, the same heat and dry conditions have fuelled 27 major wildfires; three firefighters were killed on the Colorado-Utah border, according to the US Forest Service.

The heat wave has drawn an urgent warning from the United Nations climate secretariat, which said that 26 of the 104 World Cup matches are expected to be played in conditions of extreme heat. The final, scheduled for 19 July at MetLife Stadium in New Jersey, and two quarter-finals face a high risk of exceeding safe heat thresholds, the UN report stated, using the Wet Bulb Globe Temperature index that accounts for humidity, wind, and solar radiation. Two group-stage matches have already surpassed the 28°C WBGT level at which the global players’ union FIFPRO recommends postponement. On the opening day, more than 100 people required medical attention for heat-related issues, and four were hospitalised. FIFA has mandated three-minute cooling breaks in each half for all matches, but open-air venues in Kansas City, Philadelphia, and Miami remain especially exposed.

While the NWS has issued extreme heat watches for the Northeast through Saturday, the precise peak and duration remain uncertain. Some forecast models suggest Washington, D.C., could tie its all-time high of 106°F on Friday. The UN report highlights that the heat risk is unevenly distributed, creating competitive imbalances for teams forced to play in unshaded, open-air stadiums. As of Monday evening, the heat wave was intensifying across the Plains and Midwest, with the most severe conditions expected to shift eastward by Thursday. No heat-related fatalities have been confirmed in the eastern half of the country, though local authorities continue to monitor the situation and urge residents to check on neighbours and stay hydrated.