Many factors determine vibrancy of fall foliage

The official start to fall is Thursday and for many in the region this season is indicative of change: change in temperatures, in the length of daylight hours and in the colors of the leaves.

There is a lot of science behind the beauty of this season. The astronomical transition that comes with the seasonal switch, is what triggers leafs to start changing colors. The tilt of the earth, and location within its orbit around the sun, leads to shorter days and cooler temperatures. This prompts trees to start preparing for winter. During this time, Chlorophyll which gives leaves their green tones, starts to breakdown and new colors are revealed. One of the interesting facts about fall foliage is that the vibrant colors revealed in the fall are actually the true colors of the leaves.

The vibrancy and duration of fall foliage is influenced by temperatures, sunlight and rainfall. For the brightest colors, sunny conditions are needed as well as seasonal rainfall totals with cool, but ‘freezeless’, nights.

One thing to note for fall colors in the region this year is the drought we experienced this summer. Excessive dry conditions can cause stress for trees. As a coping mechanism a tree will start preparing for winter, causing the leaves to change color and fall off. Thankfully, despite the drought earlier in the summer, recent reports show the majority of our forests are not indicating an early transition.

Soon after the beautiful colors are revealed, leaves begin to fall from the branches. This is just another way the tree prepares itself for winter. During fall, the sap inside the trees begins to thicken. This thickening process closes the veins of the tree. A thin layer begins to develop and cuts the leaf off from the branch. It then typically takes a breeze, rain or a storm to bring the leaves off the trees.

Fall foliage usually peaks for much of this region in the last couple weeks of October. We will have to see what, if any impact this summer’s drought will have on the vibrancy this fall. Though regardless, with more than 100 different species of trees in the state, fall in Ohio is always a colorful one.

Carrieann Marit is a StormCenter 7 meteorologist. Contact her at or follow her on Facebook and Twitter.

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