A push of cooler air will slash summerlike conditions across the Upper Midwest then in the Northeast beginning this weekend.
Following a flow of air originating from the Gulf of Mexico this week, air from Canada will slice eastward across the northern tier states.
According to AccuWeather Chief Meteorologist Elliot Abrams, "Even though it seemed like summer was locking in this week, the weather pattern developing for this weekend says otherwise."
A front will push southeastward across the North Central states Friday and Saturday.
The cooler air will sweep into Fargo, North Dakota, and Minneapolis by Friday, followed by Chicago and Detroit Friday night.
The forward progress of the front is likely to slow as it moves into the Northeast and the Ohio Valley later this weekend with more of an eastward push, rather than a southward plunge.
Despite this, cooler air will settle into the swath from Boston to New York City, Washington, D.C., Pittsburgh and Cincinnati on Sunday into Monday.
Temperatures will be slashed by 15-25 degrees Fahrenheit with highs in the upper 70s and 80s F replaced by highs in the 60s to lower 70s F.
Spotty showers and locally heavy, gusty thunderstorms will occur well ahead of and along the front. It could also rain a bit behind the front in some locations.
"While it will be noticeably cooler even without any rain, where it does rain behind the front for several hours, it will seem rather chilly after the recent warmth," Abrams said.
A wind off the Great Lakes or Atlantic would add to the chill in some locations.
According to AccuWeather Chief Long Range Meteorologist Paul Pastelok, "The air is not likely to get cool enough to bring frost this time."
The front is likely to stall over part of the mid-Atlantic and the southern Appalachians by early next week.
"Where the front stalls may be a focusing point for showers and locally severe thunderstorms," Abrams said.
June is the favored time of the year for severe weather in the mid-Atlantic.
A pattern change is forecast for much of the nation. The pattern will tend to favor more frequent rounds of showers and thunderstorms in the eastern half of the nation, while parts of the southern Plains and Texas get a break from the relentless thunderstorms and flooding.
Many locations in the Northeast have been abnormally dry during much of May. Some locations have been challenging for one of their driest Mays on record.
New York City has received only 0.32 of an inch of rain during the first 26 days of May. The driest May on record was in 1903, when 0.30 of an inch of rain fell.