2024 Leaf-Peeping Guide: When Fall Foliage Will Reach Peak Colors In PA

PENNSYLVANIA — The peak season for fall leaf-peeping is still more than a month away in Pennsylvania, leaving you time to plan a road trip to see fall foliage at its most brilliant.

Several online tools and predictive maps are available to guide planning, whether you plan to stay home or travel outside Pennsylvania. Leaves can start to change color as early as mid-September in northern-tier states, while the peak in some southern states is closer to November, according to The Old Farmer’s Almanac.

Its predictive map shows leaves in the Pittsburgh and Philadelphia metros will in western Pennsylvania will peak around Oct. 26, and will be past their peak by Nov. 7.

AccuWeather said the best areas to see vivid fall foliage this year will be outside of the traditionally popular tourist destinations. Leaves will be at their most vibrant around mid-October for most of the state, according to that forecast. It also suggests this year’s fall foliage show will be typical for the region, though some other areas of the United States will have more vibrant colors.

A predictive map from ExploreFall.com says leaves in Pittsburgh will reach “high color” around Oct. 26 and “peak color” around Oct. 30, while the Philadelphia region will reach “high color” around Oct. 30 and then peak around Nov. 4.

Another predictive map, from SmokyMountains.com, puts the leaf-peeping season peak at around Oct. 14 in the Philadelphia area and Oct. 21 near Pittsburgh.

No predictive tool is 100 percent accurate, but it can give leaf peepers a pretty good shot at seeing autumn leaves when they turn their most blazing reds, vibrant orange and sunny yellows.

Weather can have a big effect. Leaves need warm, sunny days, but also crisp but not freezing nights to bring about the most spectacular color show. Both rainfall and drought can also affect its vibrancy, according to the U.S. Forest Service.

According to the National Oceanic and Atmospheric Administration’s Climate Prediction Center fall temperature and precipitation forecast, we are likely to see above average temperatures over the next three months. Precipitation is expected to be slightly above normal in the Philadelphia area, and near normal in the Pittsburgh metro.

What causes the different colors?

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 thrive — 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 halt. The colors in fall’s breathtaking tapestry are influenced by other compounds, according to the national park’s website.

Beta-carotene, the same pigment that makes carrots orange, reflects the yellow and red light from the sun and gives 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.