The Science of Fall Color: Why the Leaves Change in Waves

Every fall, Rowan County comes alive with changing color — but if you’ve ever noticed that some trees seem to shift early while others hold their green a little longer, there’s a reason for that. Leaf color change doesn’t happen all at once. It occurs in waves, driven by a mix of temperature, sunlight, and moisture that vary from week to week and even from one neighborhood to another.

Temperature and Light

The main triggers for fall color are shorter daylight hours and cooler nights. As days get shorter, trees receive the signal to slow the production of chlorophyll — the pigment that gives leaves their green color. When chlorophyll fades, the other pigments that have been there all along begin to show through: yellows from carotenoids and reds from anthocyanins.

Cooler temperatures accelerate that process, but only to a point. Warm, sunny days followed by cool, crisp nights are the perfect recipe for bright, vivid color. When nights get too cold too quickly, leaves can drop before their full colors develop.

Soil Moisture and Rainfall

Another key factor is soil moisture. After a dry summer, leaves can turn early and fade quickly. When rainfall is near normal, color change is more gradual and intense. This year’s soil temperatures in Rowan County have been running a little above normal, which means color change is progressing slightly slower than usual. A few cool nights later this week may help jump-start the transition.

Tree Variety and Local Differences

Different species change color at different times. Maples and sweetgums tend to lead the way, while oaks and hickories turn later. Elevation and exposure also play a role — trees near the Yadkin River and lower-lying areas often change a few days later than those on the higher hills around the county.

The Bottom Line

Fall color across Rowan County typically peaks between late October and early November, though there are always microclimate pockets that peak earlier. If you notice waves of color moving through your neighborhood this month, it’s a perfect example of nature balancing sunlight, soil, and temperature to create one of the most beautiful transitions of the year.