A professor of biology at WCU, Mathews believes the formation of higher levels of pigments in the leaves correlates with dry weather throughout the year, especially in September. The drier the climate, the more brilliant the fall leaves tend to be, especially the bright reds, she said.

“There always will be plenty of color in the yellow and orange hues,” Mathews said. Those hues result from pigments that the leaves make year-round, hiding under the green color of chlorophyll, she said. As days get shorter and nights get colder, the chlorophyll will break down to reveal the pigments underneath. 

The red pigments are manufactured by leaves mainly in the fall in response to cooling temperatures and excess sugar production caused by lots of sun, Mathews said. She predicts the fall color peak will be during the second week of October in the higher elevations and during the third week in the mid-elevations.