CHARLOTTE, NC (WBTV) - I get this question a lot, and when I study up on it, I rarely read much about the cold autumn air.
Yet, the mountains always change color before the lower elevations. Here is what I typically hear: "Chlorophyll, which keeps the leaves green in the summer breaks down in the fall and the weaker sunlight can no longer help replenish it."
If you analyze this point, notice nothing was said about what causes the initial breakdown, only the fact the sun is too weak to replenish it.
I suspect that initial breakdown is temperature related, and the weaker sunlight then becomes a factor afterward.
Either way, as the leave's green hue fades from the loss of chlorophyll, it unmasks the other pigments of the leaves which have been there the whole time.
Opinions vary widely as to what weather conditions give the best color. I think forecasting fall foliage is even more inexact than forecasting weather.