NEW YORK — An intense and nearly historic weather pattern is cooking much of America under a dangerous heat dome this week with triple-digit temperatures in places that haven't been so hot in more than a decade.
The heat wave is especially threatening because it's hitting cities like Boston, New York and Philadelphia early in the summer when people haven't gotten their bodies adapted to the broiling conditions, several meteorologists said. The dome of high pressure that's parking over the eastern United States is trapping hot air from the Southwest that already made an uncomfortable stop in the Midwest.
A key measurement of the strength of the high pressure broke a record Monday and was the third-highest reading for any date, making for a ''near historic'' heat wave, said private meteorologist Ryan Maue, a former National Oceanic and Atmospheric Administration chief scientist. The worst of the heat was likely to peak for Northeastern cities on Tuesday, forecasters said.
''Like an air fryer, it's going to be hot," Maue said. ''This is a three-day stretch of dangerous heat that will test the mettle of city dwellers who are most vulnerable to oppressive heat waves.''
A heat dome occurs when a large area of high pressure in the upper atmosphere acts as a reservoir, trapping heat and humidity. A heat wave is the persistence of heat, usually three days or more, with unusually hot temperatures.
Where the heat will be worst
Nearly three-quarters of the country's population — 245 million people — will swelter with 90 degrees Fahrenheit (about 32 Celsius) or higher temperatures on Monday, and 33 million people, almost 10% of the country, will feel blistering 100-degree heat (about 38 Celsius) on Tuesday, Maue said. The government's heat health website showed the highest level of heat risk in swaths from Chicago to Pittsburgh and North Carolina to New York.
Those triple-digit air temperatures — with the feels-like index even worse because of humidity — are possible in places where it's unusual. New York hasn't seen 100 degrees since 2011 and Philadelphia, which is forecast to have consecutive triple-digit days, hasn't reached that mark since 2012, said Climate Central chief meteorologist Bernadette Woods Placky.