The official first day of fall in 2025 is Monday, September 22 at 2:19 p.m. Eastern Daylight Time in the Northern Hemisphere (Source). The First Day of Autumn Equinox, broken down as “Equal Nights,” is a special day where summer has officially ended, and days will only get shorter moving forward. Fall is also the season where we witness fall of leaves, fall of temperature, fall back of one hour for daylight savings. Watching the leaves change color during Fall is one of the main ways the Fall season continues to be remarkable.
Wishing everyone a very Happy Autumnal Equinox as we begin the new school year!
Source: One of our past backyards
Below is the science behind the equinoxes:
Source: It’s Okay to be SMART
Here is an alternate shorter explanation with a real demo worth watching:
Science of Fall Leaves Color Changes
A phenomenon worth exploring: how would you explain the science of Fall Leaves color changes?
Source: My Past backyard Maple Sugar Tree that was planted in 1989. Photo taken 10.22.24
Here are also some of my best captures of Fall Leaves so far through pjamal.com Photography
Cornell Campus circa 2008
Jamaica Queens circa 2005
Burlington Vermont circa 2010
Ithaca, NY circa 2015
Storm King, NY circa 2019
Prefer to read an explanation behind this phenomenon? Read below -
"The leaves of deciduous trees change color in the fall as a result of a complex chemical process. During the growing season, leaves are green because of the chlorophyll they use to absorb energy from sunlight during photosynthesis. As the season changes, temperatures drop, and days get shorter. Trees get less direct sunlight, and the chlorophyll in the leaves breaks down. The lack of chlorophyll reveals yellow and orange pigments that were already in the leaves but masked during the warmer months. Darker red leaves are the result of a chemical change: Sugars that can get trapped in the leaves produce new pigments (called anthocyanins) that weren’t part of the leaf in the growing season.
The best colors are produced when the weather is dry, sunny and cool. Places that are cloudy, damp or warm won’t see the same degree of changing color.
When trees start building a protective seal between leaves and their branches as the weather turns, they take in as many nutrients as possible from the leaves, but leaves wouldn’t survive the winter and would make trees vulnerable to damage if they remained. When the leaves are cut off from the fluid in the branches, they separate and drop to the ground"
As we start Autumnal Equinox, you might be thinking about tracking Fall Foliage https://www.explorefall.com/fall-foliage-map
Other helpful resources regarding Fall:
- Track current NY State Fall Foliage Color changes [Added 09.21.25]
