A hot and stormy Fourth of July weekend saw more than 20 cities hit record highs. While the grid was strained in some places, the power mostly stayed on.

A brutal heatwave strains power grids, threatens World Cup matches, and plays havoc with celebrations for America’s 250th independence anniversary.

Extremely dangerous heat, coupled with humidity, could result in heat index readings of 100 to 115 degrees from the Midwest to the East Coast, forecasters said.

A severe heatwave has disrupted Fourth of July celebrations across the central and eastern United States, forcing cancellations of parades, concerts, and fireworks.…