As many as 49 million people will be warned on Monday about heat in three different areas: the northeast, the plains extending to parts of the south and the northwest Pacific.
Monday will be the last in this band of extremely hot days in the mid-Atlantic and Northeast after what was a blazing hot weekend.
As of Sunday, New York City had recorded temperatures of 90 degrees Fahrenheit or higher for six consecutive days. If the Big Apple hits 90 Monday, it will be the longest heat wave since 2013.
LaGuardia Airport hit a new record this week with five consecutive days with temperatures soaring to 96 degrees or higher.
In nearby Newark, New Jersey, the temperature reached 100 degrees five days in a rowan astonishing record that has never been recorded in the city.
Boston also managed to hit triple digits on Sunday, and Washington, DC, still had a heat index reading of 98 degrees until 10 p.m. Sunday.
However, there is also good news ahead. Monday is the last extremely hot day in the northeast before the heat breaks through Tuesday. But heat warnings will continue to be posted Monday from Maryland to Boston as heat indices are expected to climb into the 100s in Philadelphia and Washington, and the upper 90s for New York City and Boston.
Monday afternoon and evening, heat will ease significantly in much of the region with thunderstorms. While the storms are good for cooling temperatures, they can be violent and cause damage in some areas.
A total of 53 million people are threatened by severe storms across the region. Damaging wind gusts pose the main threat as storms struck from Virginia to Maine Monday afternoon and evening. There is the possibility of isolated tornadoes.
Major population centers along the Interstate 95 corridor are in the risk zone during evening traffic.
Cities to watch: New York, Philadelphia, Baltimore, Boston and Washington.
While the northeast can look forward to the heat breaking Tuesday, those in the southern plains and western parts of the southeast won’t be taking a break from the extreme heat. High 90s and low 100s are available from Memphis, Tennessee, to Oklahoma City to San Antonio. Heat index values will range from 105 to over 110 in many of these areas, and the area in Tulsa, Oklahoma, is expected to reach 112.
Dallas was set to hit its 30th 100-degree day of the year on Monday.
Dangerous and prolonged heat is also starting in the Pacific Northwest, as extreme heat warnings in parts of the region remain in effect through Thursday and Friday. Seattle is expected to have four straight days of highs in the 90s Tuesday through Friday, and the Portland, Oregon area expects the highs to come out in the low 100s on Tuesday.
The highest temperatures will be in the interior of Washington state, expected to reach 115. Heat warnings currently stretch from Northern California to the Canadian border.
While this heat event isn’t expected to be as intense as last summer’s deadly heat wave that hit this region, meteorologists urged people to take warnings seriously.
Heat has also fueled the Oak Fire near Yosemite National Park. Over the weekend, the area around the fire reached 96 degrees and the temperature is expected to remain above 90 degrees for the rest of the week.
As of Monday morning, the fire had grown to 17,000 acres and was still zero percent under control.
Good news: While the heat and low humidity will continue to fuel the fire, winds are expected to be weak, which should help firefighting efforts.