Where to See Beautiful Fall Foliage in Franklin, TN, and Williamson County. As autumn arrives in Tennessee, Franklin and Williamson County come alive with vibrant fall colors, making it a top destination for leaf-peeping. In 2024, the first day of fall was September 22nd, marking the autumnal equinox—the moment when day and night are nearly equal in length. This shift signals cooler temperatures and shorter days, which cause the trees to stop producing chlorophyll, the green pigment used for photosynthesis. As the green fades, the leaves reveal beautiful shades of yellow, orange, red, and purple that were hidden beneath all along, creating the dazzling colors of fall.