FIFA has activated mandatory three-minute cooling breaks for all World Cup knockout matches as a vast heat dome settled over the tournament’s North American host cities this week. The decision, confirmed by the global governing body, came after the United States National Weather Service issued extreme heat warnings for millions of people from the Midwest to the East Coast, with heat index values forecast to peak at 46 degrees Celsius (115 degrees Fahrenheit) in some regions. The measure, which requires a pause in each half for players to rehydrate, was introduced despite criticism that it disrupts the rhythm of play, with FIFPRO, the global players’ union, having previously described such conditions as a “warning” for athlete safety.

Meteorologists in the United States describe the phenomenon as a prolonged high-pressure system that traps heat and humidity, preventing cloud formation and leading to potentially record-breaking temperatures that persist even after sunset. Alan Reppert, a senior forecaster at AccuWeather, noted that New York is likely to experience its highest temperatures since 2013, affecting the round-of-16 match in neighbouring East Rutherford, New Jersey, on 5 July. The heat dome is also bearing down on knockout fixtures in Kansas City, Philadelphia, and Toronto, where Canadian authorities activated a heat relief strategy after Environment and Climate Change Canada issued a multi-day heat warning. Three venues—Atlanta, Dallas, and Houston—offer retractable roofs and air conditioning, providing significant relief, though the concrete and asphalt surroundings of the Dallas Cowboys’ stadium amplify surface heat.

Medical experts in New Jersey and Miami have urged fans to seek shade, limit alcohol consumption, and monitor for symptoms of heat-related illness. Alina Mitina, an emergency department physician at Hackensack University Medical Center, said shaded areas “really save lives in this kind of situation,” while advising vigilance for dizziness and other early signs of heat exhaustion. The US Centers for Disease Control and Prevention warns that extreme heat can cause heat stroke, with symptoms including confusion, slurred speech, and loss of consciousness, and identifies older adults, young children, and those with heart or respiratory conditions as particularly vulnerable.

In Miami, where Argentina faces Cape Verde in the round of 16 on Friday, the city lies on the margin of the heat dome, with a forecast high of 32°C and a chance of thunderstorms. Maggie Aldousany, a clinical associate professor at the University of Miami, recommended that spectators begin hydrating two days before the match and monitor urine colour as a simple indicator of fluid balance. The heat wave is expected to move eastward as the week progresses, reaching the Washington, D.C., metropolitan area by the Independence Day weekend, when the United States marks its 250th anniversary, potentially threatening festivities and further World Cup fixtures.