EAU CLAIRE — Trees are starting to change color in Wisconsin. Those who track the changing seasons think it’s still going to be a couple weeks before the best displays.
Travel Wisconsin’s fall color report said Tuesday about 15 percent of trees in the Eau Claire area are showing some colors. It’s predicting a peak in the third week of October.
The fall foliage map from the Great Smoky Mountains website attempts to predict colors nationally. It’s anticipating a peak in this part of Wisconsin between Oct. 5-12.
Neither of the maps claims to be perfect, and the exact timing of peak colors can vary. When leaves change is primarily dictated by sunlight, but the weather can make a big difference in how bright colors are.
As the season progresses, trees shift from using green chlorophyll to produce food to making sure nutrients get back into the branches and trunk. The chlorophyll degrades, revealing colors from other compounds in the leaves. Carotenoids produce yellow, orange and brown. Anthocyanins produce red, and they’re perhaps the most variable compound each fall.
The Wisconsin Department of Natural Resources said warm, sunny days and cool — but not freezing — nights give the best hopes of bright colors. The warmth allows leaves to produce plenty of sugars during the day, and the cool temperatures keep them from flowing back into the tree.
In those conditions, trees produce additional anthocyanins to protect the leaves, ensuring the tree gets all of the nutrients it can before the leaves fall off. Since anthocyanins are red, larger amounts mean a brighter display.
The DNR said anthocyanins are primarily made during the fall, and only when needed. So reds each fall vary considerably in intensity.
The National Weather Service forecast calls for seasonably warm highs and overnight lows in the 40s and 50s. With several weeks to go, there’s no guarantee of a great display this fall. But there’s reason to keep your fingers crossed.