Above-Normal Temperatures Forecast for Much of the U.S. This Weekend

With triple-digit highs expected in the Southwest and Great Plains this weekend before spreading eastward under a dome of high pressure. Temperatures are forecast to be 15 to 25 degrees Fahrenheit warmer than normal in many areas, including at night.

A strong high-pressure system is expected to bring above-normal temperatures to large parts of the country, with the most extreme heat in the Southwest and northern plains.

“The heat doesn’t necessarily stop when it’s dark out,” said Josh Adam, a meteorologist with the National Weather Service in Bismarck, North Dakota. Temperatures in Bismarck will surpass 100 F until Tuesday, compared with typical summer readings in the 80s. The National Weather Service predicts that more than 90 U.S.

Local temperature records will be tied or broken through Wednesday, two-thirds of them overnight heat records. Temperatures will not drop below 80 F at night in Fort Lauderdale, Miami, Tampa, Galveston and Charleston. The current heat dome is one of the strongest to affect the Dakotas in 25 years, said Chad Merrill, a senior meteorologist with AccuWeather.

Record triple-digit highs are expected this weekend in Nevada, Utah, Colorado, Wyoming, Idaho, Montana, North Dakota and South Dakota. The temperature in Las Vegas is expected to hit 111 F on Saturday, said Andrew Gorelow, a meteorologist with the National Weather Service in Las Vegas. Dry thunderstorms could develop in the Rockies, increasing fire risk in already dry areas.

The current El Nino formed last month and has an 81% chance of becoming very strong by fall, the U.S. National Oceanic and Atmospheric Administration said Thursday.