Leaves change color in the fall when the length of days shorten and the amount of light reaching the trees decreases.
This year in Houston the colors have been the best I’ve seen here.
To get the brightest colors in the fall warm sunny days and very cool but not freezing nights are needed. This produces sugars which in turn produce anthocyanin pigments. Anthocyanin gives the leaves the reds, oranges and purples.
Another factor in producing brilliant fall color is the amount of moisture in the soil, droughts make for drab colors. While it’s been dry lately here, most of the early fall was rainy.