Why do leaves change color in the fall?

SYRACUSE, N.Y. - It is nearly one month into fall and the leaves are approaching peak fall foliage color! But what causes our green leaves to change to yellow, orange, or red? And how does the weather play a role in the brightness and length of color change?

It's a chemical process that occurs within the leaves that causes them to change color. As fall begins, the days become shorter, and the nights longer. This means less daylight for the leaves to produce chlorophyll. Also, with cooler temperatures the chlorophyll begins to break down leaving other chemicals within the leaves that cause color changes.

The yellow color is caused by xanthophyll, orange is from carotene, and red from anthocyanin. The yellow and orange colors are already within the leaves and show through as the green from the chlorophyll breaks down. The red color is created when the veins of the leaves shrink during fall and trap sugars, which interacts with sunlight to create a red color.

The more sunlight during late summer and fall, the brighter the colors are. Plus, we need cooler nights during fall which help to shrink the leaf veins and trap more sugars, creating brighter fall foliage colors.

During late summer and fall of this year we had many cloudy and rainy days, plus a big warm up in early fall. These factors have led to duller fall foliage colors this year and leaves have turned brown faster, falling off trees too soon.

Here's some other fun facts about leaves! There are about 200,000 leaves on a mature oak tree. About 360 dry leaves equals about 1 pound. One mature oak tree has about 550 pounds of leaves. Although, wet leaves can multiply that weight by about 4 times!

The latest fall foliage report came out today for the period of October 18th through the 24th. It shows past peak fall foliage for the entire Adirondacks and Tug Hill region, where many of the leaves are falling off the trees. The Catskills and the southeastern hills of the Southern Tier are also past peak.

The hills of Central New York including Watertown, Hamilton, and Cortland are at about 80 to 100% color change, which is at or near peak fall foliage. These areas will be seeing many of the leaves falling off the trees next week.

The lower elevations including valley locations, the Finger Lakes, and areas along the shoreline of Lake Ontario are at about 50-70% change, just past midpoint and should be at peak next week! You don't have to travel far from Central New York to see the best fall foliage this week and weekend!

Enjoy the fall foliage over the next couple weeks while it lasts! We will keep you updated on the latest fall foliage report that comes out weekly every Wednesday from the I Love NY website.