Drought, warm temps could affect fall colors this year
Summer is still here in full, hot force, but the first day of fall, Sept. 22, isn’t too far away.
That also means beautiful fall foliage isn’t far away, either.
When leaves change colors is mostly a product of decreasing amounts of daylight, and therefore usually happens about the same time every year. Last year, northern Wisconsin counties reached peak color the last week in September, with southern Wisconsin reaching peak the third week in October.
But weather plays a role, too, and this year’s drought across much of the state, plus stretches of warm weather late in August, could put a damper on this year’s colors.
“Moderate drought and warmer days and warmer nights tend to delay fall colors because the trees are not getting the signal that it’s fall yet,” said Colleen Matula, a forest silviculturist/ecologist with the Wisconsin Department of Natural Resources who works in Ashland and Bayfield counties. “The trees still think it’s summer.”
Plus, drought conditions during the growing season in northwestern and southeastern Wisconsin stressed trees.
“We are starting to see some individual trees (in Ashland and Bayfield counties) start to turn color already,” Matula said, noting that is a month earlier than they usually turn.
The recent stretch of warm weather could also affect the vibrancy of the colors.
“We need those cooler nights to amplify those bright colors, like those reds and purples,” she said.
The best weather recipe for great fall colors is a warm, wet spring followed by a summer that’s not too hot or dry and a fall with sunny days and cool, frost-free nights.
As daylight gets shorter and temperatures drop, trees slow their production of chlorophyll, which gives leaves their green color. This allows the leaves’ carotenoid pigments to shine through, giving leaves their yellow, orange and brown hues.
Weather plays a role in leaves’ red hues, which comes from a chemical called anthocyanin that trees produce to recover nutrients from leaves before they fall off. Production is high and reds are especially bright when warm, sunny days are followed by cool, but not freezing, nights.
Even with that recipe, however, an early frost, heavy rainfall or strong winds can bring down leaves and end the season early — making it all the more important to make the most of the season when it arrives.
“Enjoy it while you can. Get out there and try to get to your favorite places,” Matula said.
She noted that areas of central and northeastern Wisconsin didn’t experience the same level of drought that other parts of the state did and might put on a good show this year.
“They’ve been having pretty good rainfall, so there might be better fall color in those areas, but they still need those cool nights,” she said. “If the temperatures start changing in a month, I can envision fall color to be pretty good in those areas.”
That includes at Rib Mountain State Park, which provides views of the forested hill and nearby Wausau from an observation tower at the top.
Matula said one of her favorite spots to see fall colors is on Highway 77 from Hayward to Mellen, and Mellen to Hurley. That stretch of highway passes through the heart of the ChequamegonNicolet National Forest’s Great Divide District.
For updates on the state of fall colors in Wisconsin, check Travel Wisconsin’s Fall Color Report online, where observers report the status of colors and estimated peak in each of Wisconsin’s 72 counties. See travelwisconsin.com/ fall-color-report.
Contact Chelsey Lewis at clewis@journalsentinel.com. Follow her on Twitter at @chelseylew and @Travel MJS and Facebook at Journal Sentinel Travel.