ASHEVILLE - It might not be the most colorful forecast, but area fall foliage prognosticators are calling for an "average season." That means fall leaves might not be at their most brilliant this year, but they won’t be a bummer.

“We’ve had a fairly moderate summer with pretty good rain and no drought,” said Dr. Howard Neufeld, professor of biology at Appalachian State University, aka the “Fall color guy,” who runs a website breaking down the fall forecast.

“Temperatures have been moderate. If we have clear days into September and a succession of very cool nights and a preponderance of sunny days, that tends to bring out the red colors. Most people think it’s a good color season when the reds are bright.”

Anthocyanins, the pigment that colors red leaves, as well as strawberries and most red flowers, are made from sugar, Neufeld said. A plant makes sugar through photosynthesis when it’s sunny. If it’s cloudy and rainy, there is not as much photosynthesis, meaning fewer sugars and fewer anthocyanins.

If it’s warm, the sugars are transported out of leaf to the stems and roots, so it doesn’t build up in the leaves, he said.

The lack of drought should also be favorable for trees like tulip poplar, which tend to drop their leaves early and are sensitive to dry conditions, Neufeld said. If poplars keep their leaves longer, they should display their bright yellow showiness midway through the season.

In autumn, leaf colors emerge as the green-colored chlorophyll in leaves break down, revealing yellow, orange and red pigments that were hidden by the green.

Fall color appears first in the reds of sourwoods, dogwoods and red maples. The yellow, orange and red of trees such as walnut, tulip poplar, other maples and beech and birch show up next, and the season ends with the darker reds and browns of oaks.

Neufeld, who lives in Boone, said he has already seen a couple of sourwoods turning red near his home. Boone is about 3,300 feet in elevation, compared to Asheville’s 2,200 feet. Since WNC has a range of mountains and valleys ranging from about 2,000 feet to 6,684 feet at Mount Mitchell State Park, weather conditions in the region also vary greatly.

The elevation range combined with the rich diversity of tree species allows WNC to have a long and diverse display of color, he said.

The fall foliage forecast is looking a lot brighter than last year. Long periods of heat and drought in the spring and summer of 2016 created a spotty color show.

This spring and summer have been wetter, providing better conditions for trees. But trees also need a little push to be at their prettiest.

“The trick to getting good fall color is some kind of stress. A frost in the first week or two of October triggers the formation of the leaf division. It cuts off fluid to the leaves, and the chlorophyll is not getting replenished. Then it lets the color in the leaves show,” said Dan Pittillo, a retired biology professor at Western Carolina University who used to provide the “official” forecast each season.

Other stressors such as herbicides (spread along roadways) and disease can also provide for early and brilliant colors, but leaves then often turn brown and die sooner, Pittillo said.

While an early frost is a great stress to have, storms with high winds and rainfall will blow leaves off quickly, and the season can be over as soon as it starts.

Around Asheville, leaves start to change on the Blue Ridge Parkway first at the end of September around the Craggy Gardens, Graveyard Fields, Waterrock Knob and Grandfather Mountain areas and work their way down in elevation. Peak color is usually mid-late October.

Beverly Collins, biology professor at Western Carolina University, is in agreement about the forecast of a normal fall foliage season due to the warm, wet spring and summer.

“On balance, I’m betting against the mitigating factors (an active hurricane season, more insects feeding on leaves and above-normal temperatures through the fall), and predicting good color this year, with peak color around Cullowhee between the second and third week in October, depending on elevation.

Color will tend to change toward the end of October in Asheville.

But Neufeld likes to tell people if they drive up to the Boone area on the parkway and find that it’s past peak season, “just look down.”

“There are over 130 species of trees in the Southern Appalachians. We get quite a diversity of color. You’ll hear people say New England has the best fall color, but three species comprise most of their color – birch, beech and maple. We have dozens more species here,” Neufeld said.

“Peak color in WNC has the longest season in the country, about eight weeks. In New England their peak only lasts one to two weeks. Because color starts at high elevation first and moves downhill, if you miss it in one place, you can follow it down the mountains.”