The anthocyanins are water soluble and we get the best fall colors when we have warm days and cool but not freezing nights when the leaf is still making sugars in the fall but not removing them all from the leaf.
These excess plant sugars give us the bright colors of fall as the chlorophyll production shuts down.
Chlorophyll production slows down and then stops at slightly different times in different tree or shrub species based on day length and temperatures.
As the green chlorophyll stops production and gets used up or destroyed we can now see the yellow carotenoids that have been in the leaf all the time and the red, orange and purple tinted anthocyanins created by the autumn production of excess sugars.
Some trees, like poplars, only show the yellow.
Other trees show the yellow carotenoids and then the red or orange anthocyanin.
Others like Bradford Pears and many maples seem to go right from green to tinges of red or purple.
Day length and cool weather are the most important triggers for fall color but we get big variations in the other factors of light intensity, soil moisture and temperature that affect our deciduous trees and shrubs differently from year to year and assures that the fall color extravaganza is a new and different show each year.
Fall is also a great time to plant new trees and shrubs to create shade for future summers and dazzling fall colors in future years.