Heat Dome Brings Dangerous Daytime and Nighttime Temperatures to Much of U.S.

Npr reported. Nighttime temperatures have remained unusually warm, raising the risk of heat exhaustion and heat stroke. In the Baltimore-D.C. region and southeastern Pennsylvania including Philadelphia, the National Weather Service forecast highs in the low to mid 100s with heat indices around 110°F on Thursday.

Overnight lows were expected to stay in the low 80s, with a similar pattern forecast for Friday. Ashley Ward, director of the Heat Policy Innovation Hub at Duke University's Nicholas Institute, said temperatures well into the evening have stayed shockingly high and in some cases never dropped below 80 or 75 degrees.

"We're not getting the opportunity for recovery overnight, as we've historically seen," Ward stated.

The Fifth National Climate Assessment, published three years ago, found that nighttime temperatures are rising faster than daytime temperatures in the U.S. The report noted that the number of nights where the temperature never falls below 70°F is increasing everywhere except the Northern Great Plains.

Alex DaSilva, a meteorologist with AccuWeather, said the trends have been for overnight lows to be warmer and warmer, especially during big heat wave events.

The atmosphere retains more heat at night, and generally more humid conditions compound the effect. Eighty-eight percent of U.S. households had air conditioning installed as of 2020, according to the U.S.

Energy Information Administration. A KFF study found that Asian, Black, and Hispanic households were more likely than White households to lack air conditioning, and lower-income households were more likely to be without it than higher-income ones.