Oppressive summer heat was set to extend through the Ohio Valley and the U.S. East through this week, forecasters said Tuesday.
According to National Weather Service forecasts, extreme heat is expected to move northeast, spreading from the Mississippi Valley through the Ohio Valley and Great Lakes and, later this week, further into the East.
Much of the Mississippi Valley will face major heat risks by Wednesday, while parts of the Great Lakes and Ohio Valley may face the same by Thursday.
On Tuesday, more than 80 million people in the U.S. were under an Extreme Heat Warning, Extreme Heat Watch or Heat Advisory.
"These numbers will likely increase over the next few days as the heat wave expands northeastward and then eastward," National Weather Service forecasters said on Tuesday.
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The summer has already been hot for much of the U.S. Last month ranked as the seventh warmest June in the 131-year record. It also marked the third-warmest June on record for the contiguous U.S.
