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Fox News Weather Center

Northeast Autumnlike Chill Raises Frost Concerns

Wave after wave after wave of cool air will take the Northeast through the middle of September with an early taste of autumn. Frost will visit some areas.

Fall weather will linger before the official start of autumn on Sunday, Sept. 22, 2013.

According to Long Range Weather Expert Joe Lundberg, "Temperatures are likely to average 5 to 10 degrees below normal over the next week and then a few degrees below normal toward the middle of the month."

While a weather pattern for the next two to three weeks may not be liked by warm weather fans, it will bring great air quality most days and comfortable conditions for those doing manual labor. However, there will be a few episodes of tricky winds for those operating cranes and working on high buildings.

The pattern will translate to many cool nights and days with low humidity.

It will also mean only a few days with warm and humid conditions. These will generally be limited to the day before a new push of cool air is on the way.

Only a few opportunities for rainfall are likely with the pattern. Most of these rain dates will also be limited to the day a cool front is coming through.

According to Northeast Weather Expert Dave Dombek, "The setup will bring the potential for frost in the normally cold spots of the central Appalachians northward to interior New England Friday morning."

Temperatures could dip into the middle and upper 30s on a couple of occasions in the valleys into next week.

"With the chilly air Thursday night into Friday morning, the coldest spots of northern Pennsylvania to upstate New York could dip into the upper 20s and lower 30s," Dombek added.

The lengthening nights with clear skies can also create the perfect conditions for late-night and early-morning fog, especially in the river valleys, where and when winds diminish.

A persistent southward dip in steering winds, high in the atmosphere, known as the jet stream, will direct one Canadian air mass after another across the eastern Great Lakes, New England and the mid-Atlantic into the third week of the month.

The same southward dip in the jet stream in the Eastern states will tend to keep tropical storms and hurricanes away through the weekend into next week.

Meanwhile, a northward bulge in the jet stream over the middle of the nation will allow heat to build over the Central states into the middle of September.

According to Long Range Weather Expert Jack Boston, "Some warmth is likely to return to the Northeast during the second half of September into part of October."

While the pattern a few weeks from now may not bring record warmth, it could result in stretches of above-normal temperatures, before colder air works in during November.

During that next warmup, the door to the tropics could be opened along the Atlantic coast of the U.S.