About 5,500 feet above sea level — the magic elevation where fall color first splashes each year — the mid-September foliage along the Blue Ridge Parkway was still green as far as the eye could see and even the odd yellow specks on the landscape were just signs of drought stress.
But even as Clemson University forest ecologist Don Hagan made his annual scouting trip into Transylvania County for this fall’s foliage forecast, the temperature dropped steadily as the elevation changed, giving way from 90-plus degrees on the Clemson campus to something more autumnal in the southern Appalachians.
To Hagan, who has been making fall foliage predictions for seven years, all signs pointed to the potential for a brilliant fall color season ahead … despite the mixed signals the trees are currently receiving from the Carolina climate.
“It’s hot, and it’s been hot for quite some time,” Hagan said. “That tends to tell the plants, ‘OK, it’s still the growing season. Might as well hold onto your leaves.’ But at the same time, it’s dry, and that dry weather tends to cause plants to want to drop their leaves a little bit early. By and large, the landscape even at this elevation is still mostly green. However, things are about to start changing. We should be shifting into a more typical fall pattern here in the coming weeks.”
Typically, the cold fronts that usher in autumn bring with them cloud cover and rain, typically followed by several days of cool, clear, mild weather. And weather systems such as those are the ones that really bring out the fall color, according to Hagan.
“We haven’t had one of those systems yet, but they should be on the way here in the near future,” he said. “And when we get those, that’s really going to expedite fall color development.
“The weather that you get as you transition from the summer to the fall has a huge influence. It’s probably the biggest determinant of the quality and the timing of your fall color season. What you’d like to see is a nice gradual transition from summer to fall with that series of mild cold fronts.”
What aficionados of fall’s vibrant palette don’t want to see, however, is severe weather events of any sort. While the majority of the damage from Hurricane Florence happened nearer the coast in 2018, Hurricane Irma reached the southern Appalachians in 2017 after the leaves had already begun to turn and blew many of them off trees with its strong winds.
“The winds weren’t nearly as strong as they were when Irma was down in Florida, but it was such a massive storm that the leaves got tattered and it certainly had an impact on our fall color season that year,” Hagan said. “We got some winds from Hurricane Michael in October of last year, too. So far in 2019 we’ve been really fortunate that we haven’t had any impacts from hurricanes. Hurricane Dorian impacted the coast, but we didn’t really see any wind here. If we can get through this fall, particularly through about mid-October without any major wind events like a hurricane, I think we’re going be in good shape for a great fall color season.”
As for the length of the fall color season in the southern Appalachians this year, Hagan said it is difficult to even hazard a guess because of the unpredictability of when fall’s first freeze or first frost would come.
“Typically, when you get that first frost, your fall color season’s winding down after that and a lot of species are just going to drop their leaves after the first frost,” he said. “You typically don’t have a first frost really early in the season. Most years at this elevation it’s going to be later into September at the earliest, probably even later than that. So far, the outlook is for a fairly warm fall, maybe a little bit warmer than we’ve seen in years past, so that could delay the onset of that typical peak that you might get at this elevation.”
So while the potential for this year’s fall colors is through the roof due to abundant sunshine and no scrapes with severe weather, Hagan said those looking for a long and brilliant season featuring the best colors should hope for a gradual transition into fall — mild cold fronts, no freezing temperatures and no extreme winds.
“If we can get that from, say, mid-September on through mid-October, I think we can count on some really fantastic fall color at this elevation,” he said. “And you just don’t want those extreme events like an early frost or freeze. The thing about fall color, though, is we have this really complex landscape, so you can get a frost or freeze up here at 5,500 feet, but you might not get it down there at 4,500 feet. So as the season progresses, extreme weather doesn’t necessarily mean that the season is over region-wide. It just means that you might have to search at some lower elevations to follow that fall color.”
Prepared by Steven Bradley, Clemson University Media Relations.