The trees are showing their Fall colors of reds and yellows. The biggest driver of this annual display is the decreased photosynthesis that comes with shorter days and longer nights. But weather can have a big role in just what kind of display we might enjoy. Warm sunny days, with cool crisp nights tend to produce the most vivid colors. Warm days mean that lots of sugars, which provide the color, are being produced. The cool nights mean a gradual constriction of the veins, trapping the sugars in the leaves. Drought conditions can shorten and delay Fall color. Early freezes can speed leaf drop, also shortening the color season. While New England is famous for its Fall color, a trip through the parks and trails of Kansas provide local opportunity to enjoy not only the blazing gold of the cottonwoods and black walnuts, but the reds and russets of sumac, oak and native grasses.
Mary Knapp, Weather Data Library