The 2014 Autumnal Equinox is Tuesday, September 23rd. With cooler days in the near future, football season in full swing, and Halloween decorations in the store aisles, many are looking forward to the beautiful colors of fall. This morning, I was asked what makes the leaves change. While the answer is complex, the weather is an important factor.
According to the United States Forest Service's website, the leaves change color because the nights grow longer, so the calendar is the deciding factor. Pigments inside the leaves and the weather are also two important factors in how vivid nature's display is from year to year.
Most students can tell you that chlorophyll is what makes leaves green. As the nights get longer, the amount of chlorophyll in the leaves decreases allowing carotenoids and anthocyanins to take control of the colors of the leaves. These compounds are responsible for the yellows, oranges, browns, and reds of fall.
The weather's influence on fall color actually starts in the spring and lasts through to the drop of the last leaf before winter settles in. Cold or heat, wetness or drought, average or abnormal conditions all effect the health of the trees and the pigments in the leaves.
The best conditions to produce vivid colors according to the U.S. Forest Service are "a warm wet spring, favorable summer weather, and warm sunny fall days with cool nights." Looking back at our spring, it was on the cooler side, but wet. Our summer was pleasant, and had a bit more rain than usual. The Climate Prediction Center's seasonal outlook for our area shows above average chances for warmer than normal temperatures through the fall.
My educated guess is that we should see some nice foliage as the leaves begin to change across the state. It may not be record-breaking beauty, but I expect some patches of amazing color similar to what we have most years. Of course, I'm no botanist, so take my prediction with a grain of salt and enjoy Mother Nature's surprises.