Leaves changing colors is one of the most iconic parts of autumn in the United States, and there's still time to catch stunning fall foliage before trees become totally bare leading into winter. But why do leaves change their color in the first place?

Peak fall foliage ranges from late September into November, depending on where in the United States they're located, says Daniel Stern, Director of Horticulture at the North Carolina Botanical Garden.

Here's everything experts want you to know about fall foliage.

Why do leaves change color in the fall?

The changing color of leaves in the fall has to do with the sun being up for less and less time as autumn continues. The reason Earth experiences different seasons is because of the way its axis is tilted, which means different parts of the Earth get direct sun rays depending on the time of year, according to National Environmental Satellite, Data, and Information Service (NESDIS).

"I think about this as the trees changing gears in response to shortening days," Stern explains. "When available sunlight wanes, deciduous trees begin (to) shift from food and energy production to storage."

That shift forces trees into a "dramatic reduction" in their production of chlorophyll, which is the pigment that makes trees look green during times of the year when they're receiving lots of sunlight, Stern says. But when that sunlight becomes more scarce, chlorophyll production declines, which leads to the yellow, orange and red colors associated with fall foliage.

"The vibrancy of fall color can be greatly influenced by temperature, the intensity of sunlight and pH," Stern adds. "Additionally, the pattern of rainfall and wind in late summer and early autumn can impact the timing and duration of fall color."

Which state has the best fall colors?

Beautiful fall foliage can be found throughout most of the U.S., but some locations have been called out as particularly great spots to view the changing colors. Top locations, according to Priceline, include:

  • Hudson Valley, New York
  • Boulder, Colorado
  • Snoqualmie Valley, Washington
  • Bucks County, Pennsylvania
  • Bretton Woods, New Hampshire
  • Columbia River Gorge, Oregon
  • French Lick West Baden, Indiana
  • North Lake Tahoe, California/Nevada
  • Smugglers' Notch Pass, Vermont
  • The Berkshires, Massachusetts

"One of the best things about fall color is that it's almost ubiquitous," Stern says. "From urban street trees and city parks to rural roadsides and forests, you can find great fall foliage practically everywhere. That said, it's particularly nice when you can find some high ground with a grand view over the surrounding landscape ... I think fall color is especially nice – and most photogenic – in the low angle sunlight of early morning or late afternoon."

This article originally appeared on USA TODAY: Why do leaves change color in the fall? The science behind fall foliage

Reporting by Hannah Yasharoff, USA TODAY / USA TODAY

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