Dangerous heat wave grips U.S. with record temperatures

Tens of millions of people across the Midwest and Mid-Atlantic are under heat alerts Monday as a dangerous heat wave that began over the weekend continues to move through the region.

Tens of millions of people across the Midwest and Mid-Atlantic are under heat alerts Monday as a dangerous heat wave that began over the weekend continues to move through the region.

The rare June heat wave broke about 20 records on Sunday and is expected to break more on Monday. According to The Weather Channel, the city of Mitchell, South Dakota, broke its daily high on Saturday when temperatures climbed to 104 degrees, smashing its previous record of 101 degrees.

Records were also set on Saturday across Wyoming and Minnesota, according to The Weather Channel.

Across the Midwest, Mid-Atlantic and up to Maine, 148 million people were under heat alerts on Monday. Extreme heat warnings have been issued for 75 million people in nearly a dozen major cities, including Chicago, Boston, New York City, Pittsburgh, Philadelphia, Detroit, Baltimore, and Washington, D.C.

Bathers crowd the Lake Michigan shore Sunday in Chicago.Kiichiro Sato / APChicago up to Boston could be experiencing heat index values between 100 and 110 degrees.