People cool off with their dogs at the dog-friendly section of Montrose Beach on June 30, 2026 in Chicago, Illinois. High humidity and temperatures in the 90s with heat indices above 100 degrees are expected to remain in the city for the next several days. (Scott Olson/Getty Images) WASHINGTON — As outdoor celebrations and events marking the nation’s 250th anniversary and the World Cup reach their peak, local officials across the country are urging caution amid a heat wave blanketing many East Coast and Midwestern states. The National Weather Service has issued an extreme heat warning for parts of about 20 states, including for the entirety of Illinois, Indiana, Ohio and Kentucky. In a warning issued early Wednesday, the weather service advised that temperatures will be in the upper 90s through the weekend, with many locations reaching highs of well over 100 degrees. It estimated that the peak heat index will reach up to 115 degrees in some areas across the Mississip...