Each October, thousands gather in Banner Elk, North Carolina, to use the woolly worm to predict the winter weather. Though meteorologists rely on scientific climate data rather than caterpillars, locals and visitors continue to uphold the festive forecasting tradition.
Reading the Stripes
Using woolly worms, also called woolly bears, to predict winter weather is an old Appalachian tradition. The thirteen segments on the caterpillar’s body correspond to the thirteen weeks of winter.
Those segments range from brown to black. Tradition says more brown means a mild winter, while more black points to harsh conditions ahead.
Hayden Breckenridge works on the board of the Woolly Worm Festival. He said last year's worm prediction was quite accurate.
"I think it was like to the T. It was definitely cold. I think there was a lot more black on that worm last year, and we had a lot of snow," Breckenridge said.
More than 20,000 people come from across the country to the festival. Worms are available for purchase on-site, but participants can also register worms they find on their own. Afterwards, volunteers collect and release them back into their natural habitat.
Breckenridge said this year’s winner was a caterpillar named Wally — raced by a visitor from Louisiana.
"Our woolly worm was a lot of brown, which is good and bad depending on who you ask," he said. "Our ski folks in the ski industry would be, 'Ah, we want to see a lot of black on there. Get a lot of good fresh snow.'"
Wally’s stripes predict a cold and snowy start to the season. Then, it’s looking like it’ll be a pretty mild winter. But at the end, a cold final week with light snow or frost.
Science or Folklore?
Festival officials say the woolly worm has an 80 to 85 percent accuracy rate. It’s held that record for more than 20 years.
"They have a little better accuracy with predicting the weather than some of our other animal friends. Let's say Puxetawney Phil, maybe," Breckenridge said.
But the truth is — woolly worms can’t really predict the winter weather. According to Christopher Grover, meteorologist for the National Weather Service in Blacksburg, Virginia, a woolly worm’s behaviors and looks are based on a variety of factors including genetics, age and how much they’ve eaten.
"There's pretty much no correlation to forecasting the winter season based on the caterpillar, unfortunately," Grover said. "I don't mean to be a buzzkill on that, but that's just the scientific answer to that."
Grover said winter weather outlooks come from the Climate Prediction Center. The temperatures and precipitation predictions are divided into three categories: above, below or near normal.
There are also other atmospheric factors that go into a weather forecast. This year’s El Niño, for example, is expected to bring an above-average amount of precipitation.
And, temperature predictions also favor above-average numbers.
"There's a 38% chance, generally speaking, for North Carolina of there being above-normal temperatures for the winter season," Grover said.
While that happens to coincide with Wally’s stripes, Grover recommended staying prepared for winter weather regardless of the outlook.
"Weather can be stubborn," he said. "The atmosphere will sometimes do what it wants to do, regardless of what worms or meteorologists like myself want it to do."
Appalachian Roots
According to the National Weather Service, looking to a worm to predict the forecast goes back to colonial times. While the origins are hard to pinpoint, Appalachian traditions often stem from a blend of Native American, African American and European roots. That’s according to Trevor McKenzie, director of the Center for Appalachian Studies at Appalachian State University.
"This tradition made woolly worms into something kind of magical," he said. "You know, when you're a little kid, you kind of come up with these things, and it makes you pay attention to the natural world in a way, and makes it exciting."
The woolly worm is one of two winter weather traditions still active in Appalachia. The other — called “Beans in a Jar” — predicts the season by counting foggy August mornings.
"Sometimes we need these little narratives to kind of engage us in a way. It kind of heightens the sense of the connection between people and nature here," McKenzie said. "And I think if a woolly worm can elicit that and create some care for this place, I think that's really valuable.
Next year’s Woolly Worm Festival is already set for October 16 and 17.