U.S. East Coast heatwave to reach 100F over July 4 weekend

Millions of residents along the U.S. East Coast are facing several days of dangerous heat and humidity, with temperatures expected to reach and remain near 100F through the July 4 weekend. The National Weather Service warned that the heat index could climb as high as 115F in Washington, Philadelphia, and New York.

Forecast and warnings Maximum temperatures are projected to hit 100F in New York Central Park on Thursday and Friday, the first such readings in 12 years. The agency stated that the combination of high heat and limited overnight relief will affect people without cooling or adequate hydration.

Extreme heat warnings remained in effect Thursday from the Midwest through the Northeast. The heat is expected to ease slightly on July 4 with a chance of thunderstorms, though readings will stay above average.

Events affected President Donald Trump is scheduled to speak outdoors at a July 4 celebration in Washington on Saturday. The United States Capitol Police announced that only essential personnel would attend a rehearsal for a related concert due to heat concerns.

New York City Mayor Zohran Mamdani advised residents to stay indoors and cool. The mayor noted that a wedding scheduled at Madison Square Garden on Friday would keep attendees inside.

Regional conditions Canada is also experiencing extreme heat, with readings forecast to reach 99F in parts of Ontario. Organizers of a Toronto World Cup watch party adjusted plans, and heat warnings cover much of Quebec. The heat is driven by a persistent high-pressure system and dry soil across the Northeast, which has been in drought this year.

Forecasters said humidity will make conditions feel even hotter.