Fall Foliage Map 2018: When Autumn Leaves Peak In Pennsylvania

It still looks and feels like summer in most of the country, but fall is approaching and leaves will soon change colors to blazing reds, vibrant oranges and sunny yellows. Exactly when will that happen in Pennsylvania? You can’t know precisely, but there’s a tool to help you plan excursions around the dates when fall foliage should be at its most fabulous.

The Fall Foliage Prediction Map, found on the Smoky Mountain National Park website, includes predictions not just for the Smokies, which rise above the Tennessee-North Carolina border, but for all 50 states. In Pennsylvania, fall colors are expected to peak around the week of Oct. 15.

There are some stunning vistas right here in southeastern Pennsylvania...

• Evansburg State Park
• French Creek State Park
• Tyler State Park
• Valley Forge National Historical Park

...as well as elsewhere across the state:

• Pine Creek Gorge (the "Grand Canyon of Pennsylvania")
• World's End State Park
• Hickory Run State Park
• Delaware Water Gap National Recreation Area

If you’re planning a trip somewhere else, the Fall Foliage Prediction Map can help you pinpoint the best dates for a visit.

You probably remember from science class that the color change all starts with photosynthesis. Leaves constantly churn out chlorophyll — a key component in a plant’s ability to turn sunlight into the glucose it needs to stay healthy — from spring through early fall. Those cells saturate the leaves, making them appear green to the human eye.

But leaves aren’t green at all. Autumn is the time for leaves’ big reveal: their true color, unveiled as chlorophyll production grinds to a haltl. The colors in fall’s breathtaking tapestry are influenced by other compounds, according to the national park’s website.

For example, beta-carotenes reflect the yellow and red light from the sun and give leaves an orange hue. The production of anthocyanin, which gives leaves their vivid red color, ramps up in the fall, protecting and prolonging the leaf’s life on a tree throughout autumn.

And those yellows that make you feel as if you’re walking in a ray of sunshine?

They’re produced by flavonol, which is part of the flavonoid protein family. It’s always present in leaves, but doesn’t show itself until chlorophyll production begins to slow.

Photo by David Chapman / imageBROKER/Shutterstock