US swelters on Independence Day with over 150m people under heat alerts

Severe' and potentially record-breaking' heatwave sends temperatures soaring across US

More than 134 million people were under heat alerts on Thursday morning, as a brutal and potentially historic heatwave sent temperatures soaring across the US on Independence Day with little chance of relief over the next week, even after dark.

Forecasters warned that high overnight temperatures and the long-lasting duration of the extreme event will increase the danger, posing additional risks to human health and the rapid spread of wildfires.