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Fox News Weather Center

Fall Foliage Forecast: Warm Air May Hinder Emergence of Bright Colors in East

Weather conditions over the past few months have laid the foundation for a vibrant display of fall colors in the East, but temperatures in the coming weeks will be the determining factor, experts say.

"I think, overall, that trees are going into the autumn in good physiological condition," Dr. Marc Abrams, professor of ecosystem science and management at Penn State University, said.

"Assuming that we get a normal cooldown in late September to mid-October, the fall colors should be very good."

To date, the best displays are expected to be visible in New England, upstate New York and the Great Lakes states, but temperatures in the coming weeks could stunt the development of the East's traditional bright colors.

"The upcoming weather is very important," Abrams said.

From late September to mid-October, a cold snap paired with dry conditions helps to bring out the vibrant reds, yellows and oranges.

"We want to avoid warm, wet and windy weather during that time," he said.

According to Abrams, bright colors are also in the offing for the Appalachian Mountains and as far south as North Carolina and Tennessee.

Three primary factors influence the intensity of foliage colors during the fall season: photoperiod, cool air and water stress.

"The proper photoperiod is upon us," Michael Day, associate research professor of physiological ecology for the University of Maine, said.

"In the Northeast, trees have had above-average late summer water stress, but we are yet to have a substantial cool period over much of our area," he said.

However, forecasters predict autumn's chill may be delayed this year, proving to be bad news for leaf-peepers planning vacations around the seasonal sights.

"A very warm pattern will be found across much of the central and eastern United States through the end of September, particularly in the Great Lakes, Appalachians and Northeast, where temperatures will average well above normal," AccuWeather Meteorologist Anthony Sagliani said.

"Through the first half of October, we expect a generally warm pattern will remain in place. There are a couple of signs for a cool shot or two, but any long-lived cold snaps appear unlikely," he said.