Temperatures may hit 98 degrees in Chicago today and 91 in New York tomorrow as a late-season heat snap takes hold across the eastern U.S. before readings plummet by week’s end.
Boston, Philadelphia and Washington may also reach 90 degrees Fahrenheit (32 Celsius) or higher tomorrow, according to the National Weather Service. A heat advisory was issued for Detroit, where temperatures may be 97 today and 94 tomorrow, the weather service said.
"It is going to be a really interesting week of temperatures for the Northeast," said Rob Carolan, founder of Hometown Forecast Services Inc. in Nashua, New Hampshire. "It is going to be midsummer warm tomorrow and then a really potent cold front is going to come down from the northwest."
Above-normal temperatures in the large cities of the eastern U.S. tend to increase energy consumption because more people seek air conditioning, while cooler temperatures can have them turning up their thermostats.
Power generation accounts for 32 percent of U.S. gas demand, according to the Energy Information Administration, the Energy Department’s statistical arm.
Heat has hung on across the Midwest and Mississippi River Valley since the start of September, Carolan said. Yesterday’s high in St. Louis was 99 and it’s expected to be 98 today and 97 tomorrow.
Temperatures will average 3 degrees above normal across most of the East until Sept. 14, according to Matt Rogers, president of Commodity Weather Group LLC in Bethesda, Maryland.
For an area from southern Wisconsin to Arkansas and another from the Canadian Maritimes to the North Carolina coast, temperatures may reach 5 degrees above normal, he said.
The hottest day for those regions will be tomorrow, he said. After that, temperatures will fall as a cold front from Alberta and Saskatchewan sweeps in and highs fall into the 70s from Chicago to New York.
"Much, much cooler weather comes in for Friday," Carolan said by telephone. "Burlington, Vermont, may not make it out of the 50s on Saturday, so some big changes."
Temperatures will probably be seasonal in the eastern U.S. from Sept. 15 to Sept. 19, Rogers said. Higher readings can be expected across the northern Great Plains and into the Rocky Mountains and southern California during that period.
From Sept. 20 to Sept. 24, readings may reach 5 degrees above normal from Wyoming and Colorado east to Illinois, he said. The East Coast is forecast to remain seasonal.
The normal average temperature in New York for Sept. 18 is about 69 degrees, according to MDA Weather Services in Gaithersburg, Maryland. In Boston, it’s 65; in St. Louis, 70; Chicago, 64; and in Burbank, California, it’s 73.