A dangerous heatwave significantly disrupted Fourth of July celebrations across the central and eastern United States on Friday, July 3, 2026, leading to the cancellation or postponement of numerous parades, concerts, and fireworks displays. The sweltering conditions, exacerbated by a "heat dome" phenomenon, impacted major events like the Great American State Fair on the National Mall in Washington D.C., which temporarily closed as temperatures hit 101°F (38°C). Over 185 million Americans, more than half the U.S. population, were under heat alerts, with peak heat indexes potentially reaching 115°F (46°C). Philadelphia canceled its Salute to Independence Parade due to extreme heat, with Thursday's temperature of 103°F tying a record from 1901. Other cancellations occurred in Haddon Township, New Jersey, and Watertown, New York, while Boston delayed entry to its fireworks celebration. Officials urged the public to stay hydrated and seek shade.