World Cup Knockout Matches Proceed Amid Triple-Digit Heat Wave Across Eastern U.S.

A heat dome driving dangerous temperatures across the eastern United States has coincided with the start of the World Cup knockout stage, raising safety concerns for fans, workers, and players attending outdoor matches. The National Weather Service has issued extreme heat warnings in World Cup host cities, with conditions described as particularly severe in the Northeast.

Philadelphia is hosting a match between Paraguay and France on July 4 at 5 p.m. ET under an extreme heat warning that extends through the evening. Forecast high temperatures are around 100 degrees Fahrenheit, and the prolonged nature of the heat wave means temperatures are expected to remain elevated after sunset. The National Weather Service advisory noted that overnight low temperatures in the mid-70s to low-80s will offer no relief from the heat.

Daniel Vecellio, a climate scientist who studies extreme heat at the University of Nebraska at Omaha, told NPR that this week and the coming weekend represent a critical test for systems at the venues. He noted that high temperatures could also affect games in Kansas City and Miami, and could persist into Sunday when New Jersey hosts a 4 p.m. ET match. NPR reported that its own prior analysis of historical weather conditions found that more than one-third of the tournament's matches are at high risk for dangerous heat and humidity, and that Philadelphia was among the highest-risk host cities.