Heat on hiatus in Midwest and Northeast, but not for long
Extreme heat waves are getting hotter, more frequent and pose a major danger. Learn who’s at the highest risk, what signs to look for and what you can do.
The longest-duration heat wave of the summer just relinquished its grip on the Northeast in the last couple of days as temperatures were trimmed back across parts of the central and eastern United States. Searing heat should remain on pause through the rest of July, but the clock is ticking on seasonable temperatures as a new heat wave is on the horizon.
Blistering temperatures will once again challenge records as heat will first arrive in the Midwest next week before expanding over the Appalachians and mid-Atlantic, AccuWeather meteorologists say.
A 'heat dome' that has been responsible for the record-breaking temperatures in the Northwest will shift eastward during the first week of August. "The heat will ramp up across the Midwest and portions of the Northeast during the middle of next week into next weekend," said AccuWeather Senior Meteorologist Tony Zartman.
As this massive bubble of hot air moves to the east, temperatures will surge from near-average levels to 5-15 degrees above normal. Late July and early August are typically the hottest part of the summer for much of the northern third of the nation. Highs generally range from the mid-80s to the lower 90s.
As the core of the heat pivots from the Northwest to the North Central states, temperatures may approach or exceed 100 degrees Fahrenheit in parts of eastern Montana on Monday and western portions of the Dakotas and Nebraska on Tuesday.
Triple-digit highs may be harder to come by farther to the east from Minnesota and Iowa to Michigan and the northern parts of Illinois, Indiana and Ohio. However, temperatures are likely to at least rise into the lower 90s in these areas and could peak in the mid- to upper 90s for several days starting around midweek and continuing into the first weekend of August in the Midwest.
Even if the thermometer does not read 100 or higher, high humidity and intense sunshine are likely to push AccuWeather RealFeel® Temperatures well over the century mark in many locations, including Chicago, Minneapolis and Detroit.
The magnitude and duration of the heat are a bit less certain in the Eastern states, especially in New England.
"Portions of New York and New England may reach the 90s next week, but it is uncertain how long that will last as the core of the heat looks like it may shift back into the Plains states next weekend," Zartman said. The key will end up being the overall strength of the heat dome and the position of the jet stream across the northern tier.
If a dip in the jet stream develops and persists over New England as indicated late this week, then highs in the 90s would be held to the central Appalachians, mid-Atlantic and areas farther south. The same jet stream dip could lead to multiple rounds of showers and thunderstorms that would help ease the unusually dry conditions in much of the Northeast.
Surges in heat would still occur in New England and New York in this scenario, but they may be limited to a day or two that is interrupted by more seasonable temperatures due to the presence of clouds and showers. One such interruption could occur during the first weekend of August.
On the other hand, should the heat dome strengthen and broaden, it would force the jet stream farther to the north and make cool air intrusions harder to come by. In this case, highs in the mid- to upper 90s would occur for several days in a row across much of New England. Temperatures in the major cities from Washington, D.C., and Baltimore to Philadelphia and Newark, New Jersey, could also approach the 100-degree mark on the hottest of these days.
The last heat wave was unprecedented for places like Newark International Airport. Temperatures climbed to 100 degrees or higher for five consecutive days from July 20-24. Many locations in the Northeast amassed five to eight days in a row of 90-degree highs last week during the heat wave.
Philadelphia normally has 30 days with a high of at least 90 degrees in any given year. So far, the City of Brotherly Love has had 25 such days. July alone has had 17 days at or above 90 degrees, including eight in a row with the last heat wave from July 18 through July 25. It is possible that Philadelphia will get to at least 30 total days of 90 F or higher for 2022 by the end of next weekend and continue to add to the list during the second week of August.
New York City has had 12 days of at least 90 degrees so far this year, compared to a normal of 17 days for the entire year. Last year had exactly the normal number of days. A few days are likely to be added during the second half of next week.
Washington, D.C., is one city that is running quite far behind its normal number of 90-degree days. Although 40 typically occur every year, only 21 such days have been observed thus far. Temperatures in the 90s have been recorded as late as October, however, and there is still plenty of time for the nation’s capital to equal or surpass its normal number of 90-degree days, especially with several anticipated beginning next week.
Much of the Midwest has been on a roll as far as 90-degree temperatures this summer.
So far this year, Minneapolis has has 14 days with highs at or above 90 degrees. This has already exceeded the average of 13 days for an entire year. Farther to the south and east, Chicago has had 13 days with 90-degree temperatures or higher. The average number in any given year is 17 such days, which could easily be surpassed with the upcoming event.
Since this is typically the hottest part of the summer for much of the northern third of the nation, record-breaking temperatures may be hard to come by, but not impossible.
Most records in the major cities range from the upper 90s to low 100s in early August. Despite this, there may be a few "sitting ducks" out there where new daily high-temperature marks can be set during the heat wave.
Sometimes as a heat wave continues and the sun dries out the ground, temperatures on subsequent days can trend higher than originally projected. As a heat wave progresses, more of the sun's energy is available to heat the ground and the air. When the ground is moist, more of the sun's energy is used up during the evaporation process.
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