Vibrant fall colors expected for much of Wisconsin. Here’s when to expect leaves to change.

Quoted: Purples and reds, however, are caused by anthocyanin, pigments that are more dependent on ideal fall weather. They serve a greater purpose than just looking pretty.

“Researchers here at UW-Madison back in 2003 discovered that these anthocyanins actually act as natural sunscreen for leaves,” said David Stevens, curator of the University of Wisconsin-Madison arboretum. “What they’re doing is protecting sugars that are still in the leaf from harmful effects of the sun once that chlorophyll is gone.”