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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...

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?

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

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.

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

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