How is fall weather related to when autumn colors peak and how red leaves become?

Details

Researchers repeatedly photographed tree crowns and made visual observations on the ground to track seasonal leaf changes. Dates estimated from green and red color measurements in the images corresponded with field observations; red measurements performed well for tracking autumn changes across the eight species.

Statistical models suggested that temperature, precipitation and drought stress in autumn, along with summer heat stress, were related to when fall color peaked. The abstract does not specify a consistent earlier-or-later direction for these timing relationships. For sugar maples, higher minimum fall temperatures—or less accumulated cold—were associated with stronger red coloration.

The study links weather patterns with leaf color rather than demonstrating that weather caused the observed differences. Its findings cover the species, location and years studied, and the authors call for further research on tracking autumn changes through the redness of tree crowns.