The science behind leaf color changes and when peak color will occur

This could be a good year for leaf-peeping, thanks to the dry weather from back in September. We'll get into that in a bit, but have you ever wondered why leaves change color, to begin with?

For most of their life cycle, leaves have a plentiful supply of chlorophyll. Chlorophyll is the pigment in leaves that makes them green. As temperatures cool in the fall, trees supply less and less chlorophyll to the leaves which allows other chemicals to be used to change the leaf color.

With colder temperatures, xanthophyll causes leaves to turn yellow. Oranges come from a pigment called carotene. It's the same reason carrots are orange. Most people find the red color most beautiful and that can be traced back to a pigment called anthocyanin.

Typically, the best fall color comes when late summer is drier-than-normal and fall has sunny days and cool, crisp nights. Peak color is already being seen across the U.S.-Canadian border region and the Rocky Mountain States.

When it comes to Midwestern color, the peak for fall foliage in Minneapolis-St. Paul typically occurs around October 10th. Downriver to St. Louis, peak is October 31st.

Here in the Quad Cities, we can expect peak fall color anywhere in the third week of October.

-Meteorologist Eric Sorensen

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