A severe heat wave entered its final stretch across the eastern United States on Friday, disrupting July 4 celebrations, straining power grids and placing nearly 160 million Americans under major or extreme heat warnings. The extreme weather, intensified by climate change, also threatened to trigger severe thunderstorms as the country marked the 250th anniversary of its independence, according to the National Weather Service.

Cities open cooling centres, extended pool hours and urged residents to conserve electricity

A heat wave over the Fourth of July weekend could put millions at risk of heat-related illnesses. Here’s what to do to stay safe—and why you don’t just need to drink lots of water

High humidity is expected to make conditions feel even hotter