Predicting the Peak of Fall Foliage
By: Julie Day
Every year, thousands of onlookers crowd winding mountain roads near where I live in North Carolina to take in the gorgeous autumn foliage. And among locals, the conversation often turns to when the leaves will be at their peak color and whether this year’s show will be impressive.
Seasonal foliage predictions are a mixture of science, history, folklore, and guesswork that range from plausible to downright superstitious. While no one can say for certain when foliage will peak each year, there are some general guidelines that can help. Here are some indicators and tips to allow you plan your next autumn leaf-viewing trip.
What the Locals Say:
- Hot Dry Summer: A common adage is that if the summer is hot and dry, the leaves will turn early. Foliage forecasters look for above average summer temperatures and below average rainfall to predict an earlier, showier leaf season. While that’s generally true – trees do seem to produce more colorful pigments after dry seasons – all it takes is a rainy September to throw predictions off.
- Local Wisdom: Local residents usually have a favorite weekend to enjoy fall foliage in their area. Here in North Carolina, the third weekend in October is considered to be at or near peak foliage. Northern states often peak in early October while Southern states may not peak until Halloween or later. You can also find a wealth of information online, including maps with yearly averages as well as current reports for this year. See the links in our further information section below for a few of the better ones.
- The Maple Factor: Because of their brilliant hues of red and orange, maple trees are the benchmark for the peak of leaf season. However, the peak is less critical if you consider the beauty of the early turners (like dogwoods and tulip poplars) and the late-season hangers-on (such as oaks).
What the Experts Say:
- Leaf Color Triggers: Leaves have both yellow and green pigments, all the time. When the days shorten and temperatures drop, the green chlorophyll breaks down, revealing the yellow. An early fall frost will hasten the color change while warm, wet autumn weather will delay it.
- Red Color: According to researchers at the University of Vermont and U.S. Forest Service, maple trees show more red color when they’re stressed, especially if they’ve had lower nitrogen during the growing season. It’s thought that the red pigment is a coping mechanism that helps the leaf hang on a little longer.
- Other Factors: The effects of factors like pollution, drought, and climate change are still scientifically unknown, though it stands to reason that environmental stressors are likely to have an impact.
In all of my research, I never was able to find a definitive answer to predicting the peak date for fall foliage, though I certainly found lots of opinions! Most played the hot-and-dry card (which is a bit vague, since summers often tend to be hot and dry), or resorted to the average peak date for the area.
It was often suggested to go early rather than late, feeling that it’s better to see leaves that haven’t quite peaked than to arrive after the leaves have fallen. From my many autumns spent playing in the mountain woods, I can tell that some years are definitely better than others and the peak can fluctuate a week or so either way.
But when you get right down to it, every fall is spectacular from beginning to end. If you have a chance to see it anytime – GO!
- U.S. Fall Foliage Map (smokymountains.com)
- Regional Fall Foliage Maps (weather.com)
- Live Leaf Foliage Map (Yankee magazine)
- Average Peak Leaf Foliage Map (Yankee magazine)
- U.S. Forest Service Fall Color Hotline: 1-800-354-4595