Why Trees Change Color in Fall: The Science Behind Autumn Foliage

A Western North Carolina resident enjoys mountain fall color but wonders why it fades quickly some years.

The Pigment Story

• Chlorophyll (green): Dominant in growing season; masks other pigments. Production stops as days shorten/cool.
• Carotenoids (yellow, orange): Always present; revealed when chlorophyll fades. Stable—consistent year to year.
• Anthocyanins (red, purple): Produced in autumn from trapped sugars + light + cool nights. Highly variable—depends on weather.

Why Color Duration Varies

Your Mountains: Microclimate Matters

Elevation, aspect, and species mix create patchwork color. A warm, wet October (common some years) = muted, short display. A crisp, dry, sunny October = spectacular, long-lasting color.

Resource

Science Made Simple: Why Leaves Change Color — clear diagrams and explanations.

Bottom Line

Color duration depends on autumn weather: sunny days + cool nights = long, vivid show; warm/wet/freeze = short, dull show. You can't control it—just enjoy the good years.