This Map Predicts Peak Fall Color Change in Every US County

Autumn is finally around the corner, though it may not feel like it at the moment. Much of the country is still baking in very summer-like heat, but cooler weather and glorious fall color change are fast approaching.

And planning your next autumn leaf-peeping hike just got easier, thanks to this nifty fall foliage prediction map. The interactive model shows the predicted intensity of fall color change in every US county on a week-to-week basis.

The map forecasts color change through the week of November 15th. Users can toggle through the weeks to see the changing color landscape over that time period.

“Our experience combined with a scheduled mid-season update has us especially confident about this year’s predictions,” says David Angotti, the founder of and the statistical expert behind the map.

According to the map, patchy color change has already started throughout much of the Rocky Mountains, West Virginia, northern New England, and the Great Lakes region. Those areas are also predicted to be the first in the nation to reach peak color in late September.

Most regions of the country will experience at least some color change by early October. Trees will be past peak almost everywhere by November 15th, if this year’s predictions hold water.

READ NEXT – Best Sections of the Appalachian Trail to Hike in Fall.

Leaf Peeping Tourism

fall color

Western larches in Glacier National Park turn gold in autumn before shedding their needles for winter. Photo via.

Leaf peeping is a significant driver of tourism in the United States. Every autumn, hikers, sightseers, and photographers flock to popular fall foliage regions to enjoy the spectacle.

The New England region alone brings in billions in tourist revenue each autumn (theoretically early October this year) thanks to its brilliantly hued maple trees.

The Rocky Mountains are also popular for fall foliage viewing. The region is home to quaking aspens and, in the northern regions, larches, which turn large swaths of the mountains gold in late September.

What factors influence fall color change?

In autumn, chlorophyll concentrations in leaves—which give them their summertime green hue—decrease as the days get shorter, allowing yellow and red pigments to shine through instead. That happens every year without much variation because the days always get shorter in fall.

But according to the US Forest Service, temperature and moisture also strongly affect the intensity of color change each year. “A warm wet spring, favorable summer weather, and warm sunny fall days with cool nights should produce the most brilliant autumn colors.”

These conditions allow trees to produce more sugars, which in turn boost anthocyanin levels. Anthocyanin is a plant pigment that gives leaves their brilliant red autumn hues.

READ NEXT – 20 Fall Foliage Hiking Photos to Brighten Up Your Day.

It’s difficult to predict the timing and intensity of color change year to year because so many variables affect it. Climate change also affects fall foliage, further complicating matters, though these impacts are not yet well understood.

Angotti’s model uses millions of data points, including temperature and precipitation data and historic leaf peak trends, to output predictions. “Similar to any meteorological forecast, leaf predictions will never be 100% accurate,” he acknowledges.

“However, after publishing our predictive fall foliage map for nearly a decade, we are quite confident in our data sources, process, and algorithm.”

This Year’s Outlook’s fall 2021 temperature outlook suggests near-average temperatures for September-November throughout much of the US, though parts of the West and Midwest are expected to be warmer than usual. Meanwhile, this spring was warmer and drier than average across the country.

How the 2021 fall foliage season will play out in real life remains to be seen.

Do you have 2021 fall foliage hiking photos you’re especially proud of? Click the button below to submit your pictures for a chance to be featured on The Trek.

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