Heat wave to push temperatures into triple digits across much of U.S.

A large bubble of heat will drift slowly across the United States into next week, shifting out of the West and into the Central States and finally the East. The heat wave will bring the highest temperatures of the year so far, with some areas possibly reaching triple digits, AccuWeather meteorologists warn.

With limited days of warmth over much of the northern Plains, Midwest and Northeast so far this year, the surging heat could catch people off guard as it will be accompanied by some of the most intense sunshine of the year along with high humidity levels.

Energy demands will spike, and the risk of heat-related illness will rise sharply. Cooling centers may need to be opened. Neighborhoods will be abuzz with the hum of fans and air conditioners. People are encouraged to minimize physical exertion during the midday and afternoon hours when AccuWeather RealFeel® Temperatures will be at their highest and 5-15 degrees Fahrenheit above the actual temperature.

As areas west of the Rockies experience a significant cooldown, sweltering heat will grip the center of the nation from Friday through Sunday.

"To finish up the week, temperatures can challenge daily record highs from the central Rockies to the Plains and Midwest," AccuWeather Meteorologist Alex Duffus said. Temperatures will climb into the upper 90s and low 100s, which is 10-20 degrees above the historical averages for the second half of June."

"The magnitude and longevity of this heat wave will be a shock to the system," AccuWeather Senior Meteorologist Chad Merrill said.

Denver will experience at least a four-day stretch with highs in the 90s or greater from Thursday through Sunday, including a couple of days with highs above 100 from Friday to Saturday. This will be the first triple-digit heat of the year in Denver.

"Detroit hasn't even hit 90 degrees this year and may have a stretch of at least seven days at or above this mark coming up starting on Saturday," Merrill explained, "This would tie for the third longest streak of consecutive 90-degree days. The last time Detroit had at least seven consecutive days at or above 90 degrees was July 1-9, 2020."

Early next week, the heat wave will continue to progress eastward, focusing on the Great Lakes, the central Appalachians, the mid-Atlantic and New England.

"From June 23-25, dangerous heat will focus on the Northeast region with widespread highs in the 90s and some areas approaching or exceeding 100 F, resulting in a surge in energy demands and the need to limit exposure to the extreme conditions," Duffus said.

The effects of the heat dome in the Central and East states will be somewhat limited by the moist ground in many places, as some of the sun's energy will be used up in evaporating the moisture rather than heating the air. If the same heat dome were to occur over a dry landscape, temperatures could easily reach or exceed 100 over a broad area rather than a few cities.

The moisture evaporating from the moist ground will add to the already humid atmosphere and make for jungle-like conditions both during the day and night.

Thunderstorm activity may be few and far between in many areas amid the heat, a change from recent weeks. However, on the northern edge of the heat dome, across portions of the Great Lakes, upstate New York and New England, one or more complexes of drenching, gusty thunderstorms may roll through.

"Washington, D.C., has only experienced two consecutive days with highs in the 90s so far this year," Merrill said. "The city may have a stretch of seven consecutive days with temperatures of 90 or greater, starting on Sunday."

Starting on Monday, New York City is likely to have five consecutive days with high temperatures of 90 or greater. Boston, which will be on the edge of the heat dome and may experience interruptions from thunderstorms riding down from the northwest, is only likely to have a couple of days in a row with highs of 90 or greater.

The heat dome will be challenged from the south, west and north later next week as clouds, showers and thunderstorms return. But a pocket in the mid-Atlantic region could avoid the moisture and the downturn in temperatures for an extended period.

With the surge of heat with high humidity coming, people are urged to take it easy, stay hydrated and keep close tabs on young children and the elderly.