@314goods: THE YELLOW WAS THERE ALL SUMMER. Leaves look green because chlorophyll dominates the view. As days shorten and chlorophyll production slows, that green breaks down and yellow and orange pigments that were already present become visible. Reds can form through additional chemical changes in some species. Save this for your next leaf-peeping walk. Source: USDA Forest Service, “Why Leaves Change Color” — https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprd3817419.pdf Visual: licensed nature photograph.