Bright sunny days, moderate rain fall and cool crisp fall nights will likely yield a vibrant fall foliage display.
Nature and Fall Foliage Photographer ForestWander from West Virginia claims that a colorful fall foliage display depends upon many variables; these conditions include the amount of rain fall, a gradual transition to colder weather, the average of summer temperatures and bright sunshiny fall days.
Weather and climate patterns are ideal for fall foliage displays when the leaves are exposed to bright sunshine during the day and the temperatures are cool and crisp in the night (not freezing). These conditions combined with adequate rainfall help to produce sugars in the leaf, and as a result, the veins gradually close in the leaf allowing it produce brightly colored pigments.
Contrary to popular belief autumn leaves do not change color because they are dying from the cold. Actually the color spectrum from the sun changes during the fall season due to the different angle in which the sun penetrates the atmosphere. This different color spectrum and the longer nights trigger a naturally occurring change in the production of chlorophyll.
Since the autumn days are not as long and the sunlight is much less intense, less chlorophyll is produced and the colors of the leaves will then begin to change. This can be demonstrated somewhat by our own skin that changes color depth when tanned by the sun, although humans do not produce chlorophyll as a result of the sun but rather produce melanin. The less light exposure the lighter the color our skin exhibits.
As a result of the recent weather pattern of cool nights and bright sunlit days it is likely that the eastern U.S. will experience beautiful fall foliage displays throughout the forests and mountains. Get your camera ready leaf peepers; this year may be much better than the recent years that experienced draught and dramatic temperature changes.