The time of year has arrived when higher elevations, as well as communities near the U.S.-Canada border, are beginning to notice the first changes in leaves in what is yet another sign that meteorological fall is underway.
According to ground observations and satellite data, signs of fall foliage have already been reported in the higher elevations of Colorado, North Carolina and New York, with more communities being added to the list each day.
Some leaf peepers may notice changing colors outside of the high country, but experts point to climate stress and diseases that may be responsible for premature browning and leaf droppage.
The science behind changing leaves is rooted in a plant’s chlorophyll and photosynthesis process.
During spring and summer, chlorophyll allows trees to convert sunlight into energy, but as daylight decreases and temperatures cool, chlorophyll breaks down. This helps reveal yellows, oranges and reds that were previously masked by the dominant green pigment.
The process accelerates in September, when much of the U.S. loses between two and three minutes of daylight per day, as North America heads towards the winter solstice.
Changes in the color of vegetation were reported in Alaska in mid-August, with the Last Frontier also likely to reach peak status before any other states.
Photo from Appalachian State University in Boone, N.C. (9/6/2025)
(Appalachian State University / FOX Weather)
FIRST SIGNS OF CHANGING LEAVES SPOTTED IN ALASKA AS SEASONAL SHIFT BEGINS
One of the simplest ways for leaf peepers to track the changing leaves is by following the nation’s interstate highways.
Even-numbered interstates run east to west across the country and provide convenient benchmarks for when foliage typically peaks.
Interstate 90, which stretches more than 3,000 miles from Seattle to Boston, is usually the first corridor where leaves change outside the mountainous regions.
Peak season along the northern tier of the country usually happens in mid-October before reaching more southern latitudes.
Farther south, along Interstate 70, leaves generally begin changing by late September, with their peak around Halloween.
The last corridor to typically witness changes is Interstate 10, which runs from Southern California to Jacksonville, Florida.
Spotty color begins to appear there by the end of October, with a peak in late November or early December.
Average Peak Fall Foliage
(FOX Weather)
TRAVELING FOR FALL FOLIAGE? HERE’S WHERE YOU SHOULD GO AND WHEN
The timing and intensity of the annual event vary by several weeks across the country, with local climate conditions playing a crucial role in determining the longevity of the season.
For instance, regions that experience a lack of precipitation are likely to see more muted colors, with leaves potentially turning brown and falling prematurely.
Similarly, areas that endure a rainy and blustery fall may find their foliage season shortened, preventing leaves from reaching their full potential.
Areas that aren’t dealing with drought conditions and are accustomed to sunny skies may extend their peak window longer than what is typical.
An 84-year-old former pilot got to check an item off her bucket-list when she took the controls during a flight over the fall colors in New Hampshire.
