Heat dome expands across the central United States, creating dangerous conditions for millions

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High humidity across parts of the region is compounding the danger, pushing heat index values — how the temperature actually feels on the body — well above the measured air temperature in states including Iowa and Arizona.

Some areas of the US are about to be hit by a huge heatwave, which could see temperatures soar up to 122F (50C).

The oppressive midsummer weather was forecast to affect a huge stretch of the country, from the desert Southwest to the Gulf Coast and reaching up into the Midwest and Great Plains.