(NBC NEWS) Warnings of blistering temperatures were expanded Friday to include parts of 26 states as a days-long "heat dome" scorched much of the nation, triggering dangerous thunderstorms.
From Austin to Boston, temperatures were forecast to push triple digits, with the heat index — a measure of how hot is feels — reaching 115 degrees in isolated spots. As many as 122 million Americans were under some sort of heat advisory, in an area that stretches 830,000 square miles.
And it could be even hotter on Saturday.
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