Peoria, Ill. (WMBD) – Fall officially begins on Tuesday, September 22nd and 8:31 am, the precise moment the Sun’s center crosses Earth’s Equator, a moment is called the Autumnal (Fall) Equinox. The term equinox is a Latin derived term meaning equal nights which is named for the approximate equal length of days and nights during the Spring and Fall Equinoxes.
While fall hasn’t officially begun, you may have noticed that a few trees are starting to show their true colors. This begs the question, when is the foliage expected to peak? While some patchy foliage is typically seen at the end of September and early October, peak foliage in central and northern Illinois tends to come at the middle to end of October.
Why do the leaves change color?
Many people believe that the changing colors is the result of colder temperatures, but that’s not the case. Instead it is due to the change in seasons and shorter days. With less sunlight, Photosynthesis (the process that uses sunlight and water to create glucose) cannot occur and the green Chlorophyll disappears. Once the Chlorophyll is gone, other pigments called xanthophylls and carotenoids become visible allowing leaves to turn red, orange and yellow.
Now, the quality of the fall foliage displays across the country depend highly on temperatures and sunlight. Sunny and warm days followed by cool, frost-less nights typically lead to the best displays of fall colors while a good storm that brings a soaking rain and strong winds can make for a less than stunning display.