Fall forecast calls for impressive autumn foliage in upstate NY

Leaf peepers rejoice — conditions appear to be aligning for vibrant fall colors in western and central New York and the North Country.

AccuWeather predicts especially colorful fall foliage across more than 20 states this autumn, though not in traditional prime areas like much of New England.

“The better spots for colorful fall foliage are forecast to be in parts of upstate New York, western New York, and central and northern Pennsylvania,” said Paul Pastelok, AccuWeather lead long-range expert, in a statement. “Those areas have had a little bit less rainfall. Through September, we may be missing out on the heaviest rainfall. Cooler nights will bring out some of those brighter colors in those areas.”

What weather makes for vibrant fall foliage?

The degree and brilliance of leaf colors in autumn is connected to the weather conditions before and after chlorophyll, the pigment that makes leaves greens and facilitates photosynthesis, dwindles, according to the U.S. Forest Service. The biggest factors are temperature and moisture. Warm, sunny days and cool, but not freezing, nights are needed for the generation of sugar within deciduous trees — those that lose their leaves.

Summer drought can stress trees and cause them to lose leaves or start color production prematurely , according to information from Harvard Forest. A summer on par with normal precipitation amounts has prevented drought conditions forming in upstate New York. A warm period during fall can also cause premature leaf drop, leading to a less vibrant display .

The East Coast has received a lot of precipitation already, which can lead to more dull yellow and brown foliage this fall, Pastelok said. On the flipside, severe droughts in the Mid-Atlantic states like Virginia and Maryland have stressed trees, prompting a prediction of dull colors and earlier drop off.

More: What the Old Farmer's Almanac is predicting for fall weather in New York

How leaves change color in the fall

As the amount of daylight gets shorter in the fall, chlorophyll production in leaves slows down and eventually stops. Chlorophyll gives leaves a green color, so when these pigments are not visible, carotenoids, which produce yellow, orange and brown colors, show through, according to the Virginia Department of Forestry.

Bright light and excess plant sugars are abundant during the season, and they help produce anthocyanins. Anthocyanin is found within cell sap, not the membrane, and more acidic sap presents as a bright red. It’s the same pigment that creates the red skin of apples and purple skin of grapes. There are numerous native trees that turn red or purple in the fall including red maples, red oak, white ash and sugar maples.

Trees that turn yellow in the fall are more consistent year-to-year because leaves always contain carotenoids, which are always present in leaves, even when they’re green.

Where and when leaves are predicted to change

Here's a county-by-county breakdown of how the foliage will change across the U.S. this year.

More: Fall foliage forecast: These maps show when leaf color will peak in New York

Climate change and fall foliage

The timing of fall foliage will be impacted by the warming climate, with a majority of years likely experiencing a delayed color change and peak foliage, said Brett Anderson, AccuWeather climate expert, in a statement.

“In some areas, the average peak foliage time has been pushed back by as much as one to two weeks, compared to what it was back in the 1970-1980s,” he said.

Climate change is expected to result in more dull colors in general due to a decline in clear, cool nights in early fall, Anderson said. More extreme weather, including rain and windstorms, could cause premature leaf loss; more wet and humid conditions could also result in more fungus growth, which dulls colors, and less insect die-off, which can damage trees during the growing season.

The average fall temperature in Rochester has warmed 2.1 degrees since 1970, according to data collected by Climate Central. There is also an additional 8 days above the historic norm than in 1970.

-This story includes reporting from USA Today.

— Steve Howe reports on weather, climate and the Great Lakes for the Democrat and Chronicle. An RIT graduate, he has covered myriad topics over the years, including public safety, local government, national politics and economic development in New York and Utah.

This article originally appeared on Rochester Democrat and Chronicle: Fall forecast calls for impressive autumn foliage in upstate NY