Central and Eastern U.S. under heat wave through Fourth of July weekend

A prolonged heat wave is affecting most of the central and eastern United States as of June 30, 2026, with extreme conditions forecast to intensify through the Fourth of July weekend. Highs in the 90s are expected as far north as northern Michigan and northern Wisconsin, while heat indices reach triple digits in Milwaukee, Chicago, St. Louis and Minneapolis.

The National Weather Service said the extreme heat will peak Tuesday through Thursday in the Midwest and Mississippi Valley before shifting eastward into the Ohio Valley and East Coast. , New York City and Boston could each reach 100 degrees by Thursday, with dangerous heat indices of 100 to 110 degrees forecast in those cities plus Philadelphia and Richmond.

Overnight lows in parts of the Mid-Atlantic may remain above 80 degrees, and parts of the I-95 corridor could see triple-digit highs each afternoon from Thursday through Saturday.

Approximately 230 million people, or roughly two-thirds of the U.S. population, could be exposed to extreme heat during the week. Outdoor activities such as summer camps have been cancelled, and cooling centers are open in Columbus, Ohio, where the city has waived bus fares and public pool entry fees.

The South will continue to see highs above 90 degrees, with some locations from Texas to the Carolinas exceeding 100 degrees and heat indices over 100. Near-record or possibly record energy usage is expected for mid-Atlantic power providers, with some companies potentially implementing power cuts on Thursday to stabilize the grid, according to AccuWeather senior meteorologist Alan Reppert.

Philadelphia's all-time record high of 106 degrees, set in 1918, could be approached.