Widespread triple-digit AccuWeather RealFeel® Temperatures created dangerous conditions for residents and visitors across the mid-Atlantic, including at all of the major cities along the I-95 corridor, before noon EDT on Sunday.
"The actual high of 100 F in Baltimore on Saturday was the city's first triple-digit reading since July 25, 2016," according to AccuWeather Senior Meteorologist Kristina Pydynowski.
"While the heat has been extreme during the daylight hours, the nights have offered no relief," she added.
The "low" temperature in Boston on Sunday morning sat at 83 F. For comparison, the average high for the day is 82 F.
Atlantic City hit 100 F on Sunday, breaking a record from 1981 of 99 F.
Many records came close to beating the record high temperatures on Sunday, but ended up tying previous records instead. Bridgeport, Connecticut, tied a record high of 98 F, last set in 1991. Also, John F. Kennedy International Airport in New York hit 99 F, tying a record from 1991.
From the Northeast to New Mexico, at least seven record high temperatures fell on Saturday.