Longer and cooler nights trigger changes in the pigments that give leaves their color. Conditions that create the brightest fall colors include ample summer rainfall, followed by a fairly dry September with cool nights and sunny days.
This week, look for the early harbingers of fall - the yellow of tulip-poplars, bright reds of black gum and sumacs, and duller reds of dogwood and poison ivy can be seen in patches all over the state. Trees that have been stressed over the summer may also change early, often with duller colors than usual.
For a simple explanation of why leaves change color, take a look at "Virginia in the Fall," a free online publication in the Education section of our website.