Leaf Expert: Fall's Splendor Hinges On September Weather

Over the next three months, tens of thousands of tourists will spend nearly $1 billion during their visits to the mountains of North Carolina, and they're hoping for a vibrant show of fall colors.

Appalachian State University biology professor Howie Neufeld watches the changes closely. He studies the physiology of plants, and he's what you might call a "leaf expert." He says this month's weather is an especially important predictor of the quality of the colors we see this season.

That's when leaves begin their slow shift from creating green chlorophyll to the reddish anthocyanins. Anthocyanins are located in the upper layers of leaves to protect them from sunlight that can damage the leaves' lower layers. He says if it's cool and clear with lots of sun, the more color you're going to see on the trees. 

"Think about it – if you mix red and green together, you get kind of a brownish color," says Neufeld. "But when the chlorophyll goes away, that red is able to be seen just in its isolation and you get that real bright red color. So if we have those clear days, you'll get high amounts of anthocyanins and bright red colors."

Neufeld says the leaves are just now beginning to turn at some of our state's highest elevations in and around Boone. He's hopeful that the weather conditions continue to cooperate. 

"What we want to hope for is that we don't get a real hard freeze, because then that can knock some of the leaves off the trees before they reach their peak color," he says. "The other thing we don't want is a severe wind and rain storm right when the colors are peaking because that's also when the leaves are starting to lose their grip on the tree and they can fall off really easily."

You can follow Neufeld's daily fall foliage updates on Facebook at The Fall Color Guy.