Build your own autumn
Change the weather and watch the canopy respond. This is a teaching experiment for curious leaf peepers and classrooms — the real forecast lives on the map.
Set the weather
Your simulated season
This is a simplified teaching model built to show how weather pushes color around. It is not the WhereLeavesPeak forecast and should not be used to plan a trip.
Why leaves turn
Chlorophyll — the green
Trees make chlorophyll all summer to turn sunlight into food. As days shorten, production stops and the green fades away, uncovering what was already there.
Carotenoids — yellow & orange
These pigments sit inside the leaf all year. They show up every autumn once the green is gone, which is why yellows are the most dependable color.
Anthocyanins — red & purple
These are made fresh each fall. Sunny days build sugar in the leaf and cool nights keep it there, and that trapped sugar becomes red pigment. Warm nights or gray weeks mean fewer reds.
Tannins — brown
What's left after the other pigments break down. Drought, hard freezes and storms move leaves to brown and drop them earlier.