Fall Foliage: why leaves change color

Weather News

Fall foliage is starting to show up in the Pioneer Valley.

In the spring and summer, leaves create food for tree growth through cells containing chlorophyll, which gives the leaves their green color.

So the vibrant reds, oranges and sometime purples are actually there year-round, just in the warmest seasons with the longest daylight hours, the green overtakes those colors.

But Fall is when daylight hours grow shorter and temperatures start dropping, ending the leaves’ food-making process. So the chlorophyll breaks down, revealing the vibrant colors beneath. 

Temperatures play a role, but for the most part they only influence the intensity of color. Low temperatures above freezing will help form brighter reds in maple trees, but an early frost actually weakens the red color.

The best overall conditions for bright reds, oranges and yellows during the fall season? A clear, dry and cool but not below-freezing day.

And the leaves are starting to change here in western Massachusetts. Some trees are still green, but others are nearing their peak.

Overall, we’re still in the turning phase. I don’t know about you, but I’m excited for the next few weeks. 

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