Linda Poon is a staff writer at CityLab covering science and urban technology, including smart cities and climate change. She previously covered global health and development for NPR’s Goats and Soda blog.
Much of the country won’t see those vibrant oranges and reds until mid-October, which leaves plenty of time for leaf peepers to plan their autumn road trips.
Nothing signals the arrival of autumn quite like the changing colors of the leaves. The mass transformation from green to orange to fiery red confirms that fall has finally taken over.
But even as the September equinox marks the official start of the autumn season on the 23rd, it won’t look like fall for much of the country. Peak foliage, experts say, will likely be delayed this year.
According to the annual fall foliage prediction map by the cabin rental site Smoky Mountains, only a handful of states in the upper midwest and the tippy-top of New England will see partial colors by September 21, and leaves should start turning red by the end of the following week, around September 28.
So for the most enthusiastic leaf peepers, this is the time to start planning your scenic drives, hiking adventures, and photo excursions.
As for the rest of us farther south, we’ll likely have to wait until mid-October before the leaves start changing across the lower half of the country. Peak foliage across the U.S. will most likely appear between the last week of October and the start of November.
The map, which lets users adjust a slider to see weekly predictions between September and November, draws from historical and forecasted precipitation, daylight hours, and temperature data from private sources and public ones like the National Oceanic and Atmospheric Administration. The team behind it claims the predictions are fairly accurate; this is their sixth time making the map.
In fact, in the two- to three-week period that typically makes up “leaf peeping season,” it’s a big business opportunity for the small towns that surround popular parks and hiking trails. States like New York and New Hampshire, which drew in 3 million tourists last fall, have their own foliage trackers, being sure not to leave such a strong economic driver up to chance. Other popular locations, like Virginia’s Shenandoah Valley, have turned to crowdsourcing to track nature’s big ungreening.
Perhaps not surprisingly, climate change poses a threat to those towns as scientists say it could delay peak foliage and dull the colors. Last year’s foliage season was deemed “bizarre” by the Foliage Network for the abnormal delay of fall colors, particularly in the mid-Atlantic region. In the 10 years that the group has been monitoring weekly leaf change across the country, 2018 was the first time they reported almost no leaf-color change by the second half of October. And when colors did change in, say, Maryland, there were only pockets of that vibrant orange and red. Green and brown largely dominated.
In short, as plant physiologist Howie Neufeld writes on his blog, trees use day length and temperature as signals to prepare for winter by starting the process that strips leaves of chlorophyll (which gives them their green color) and creates anthocyanins, which turn them red. Warmer temperatures later in the year will delay this process, while an increasingly extreme mismatch between the two factors could “disrupt the synchrony of color development,” Neufeld writes, leading to more muted colors.
But don’t despair: The leaves will are sure to change, and already are in some parts of the country. Even if they don’t reach an intense red, the foliage is sure to be a sight to see.