Millions of people across central and eastern US under ‘heat dome’ warning

Temperatures at or above 100F expected as extreme hot air and humidity are trapped in atmosphere

Scores of millions of people across the central and eastern US will swelter under the summer's first heat dome" beginning this weekend and extending through the end of next week as extreme hot air and humidity get trapped in the atmosphere.

The arrival of the heatwave coincides with Friday's first day of summer and will bring temperatures at or above 100F (37.7C) to numerous cities as it moves to the east of the US in the coming days, forecasters say.