09/22/2025
First Day of Fall
The fall equinox and the first day of autumn arrive today: Monday, September 22, 2025, at 2:19 P.M. EDT in the Northern Hemisphere. The autumnal equinox is an astronomical event that marks the start of autumn (or fall). In the Northern Hemisphere, the autumnal equinox occurs in September; in the Southern Hemisphere, it occurs in March. For those in the Northern Hemisphere, when the Sun crosses the equator going from north to south, this marks the autumnal equinox; when it crosses from south to north, this marks the vernal equinox. In the Southern Hemisphere, itâs the reverse.
After the autumnal equinox, days become shorter than nights as the Sun continues to rise later and nightfall arrives earlier.
For those in the Northern Hemisphere, when the Sun crosses the equator going from north to south, this marks the autumnal equinox; when it crosses from south to north, this marks the vernal equinox. In the Southern Hemisphere, itâs the reverse.
After the autumnal equinox, days become shorter than nights as the Sun continues to rise later and nightfall arrives earlier.
For those in the Northern Hemisphere, when the Sun crosses the equator going from north to south, this marks the autumnal equinox; when it crosses from south to north, this marks the vernal equinox. In the Southern Hemisphere, itâs the reverse.
After the autumnal equinox, days become shorter than nights as the Sun continues to rise later and nightfall arrives earlier.
For those in the Northern Hemisphere, when the Sun crosses the equator going from north to south, this marks the autumnal equinox; when it crosses from south to north, this marks the vernal equinox. In the Southern Hemisphere, itâs the reverse.
After the autumnal equinox, days become shorter than nights as the Sun continues to rise later and nightfall arrives earlier.
For those in the Northern Hemisphere, when the Sun crosses the equator going from north to south, this marks the autumnal equinox; when it crosses from south to north, this marks the vernal equinox. In the Southern Hemisphere, itâs the reverse.
After the autumnal equinox, days become shorter than nights as the Sun continues to rise later and nightfall arrives earlier.
Note that fall foliage isnât due to current weather conditions. This is a common misconception. Leaves change color because of the amount of daylight and photosynthesis.
Fallâs fiery colors are one of natureâs most stunning shows, but did you know those brilliant reds, oranges, and yellows were hiding all summer long? Itâs true! The vibrant hues you see when the leaves change arenât just about chilly weatherâtheyâre all about sunlight, chemistry, and clever trees getting ready for winter. Letâs dive into the fascinating science behind why leaves change color and how weather and tree types create the perfect autumn masterpiece.
Why Do Trees Change Color?
Nature is so fascinating! The main reason for the eye-popping color change is not autumnâs chilly weather but sunlightâor rather, the lack of daylight. Day and night are roughly equal in length on the autumnal equinox in late September, but afterward, nights are growing longer and days shorter.
As the autumn days shrink, the reduced daylight tells deciduous plants that itâs time to stop gathering energy and get ready for the dormant seasonâwinter.
Ancient Autumn Equinox Celebrations Around the World
The fall equinox has been a day of celebration for cultures since ancient days, when people tracked the transitions of Earthâs journeys around the Sun.
⢠At Machu Picchu in Peru, an ancient stone monument called Intihuatanaâmeaning âHitching Post of the Sunââserves as a solar clock to mark the dates of the equinoxes and solstices.
⢠In Mexico, the Mayans built a giant pyramid called ChichĂŠn ItzĂĄ. On the equinoxes, the light looks like a snake slithering down the pyramidâs steps.
⢠In England, Stonehenge was also built with the equinoxes and solstices in mind.
Catherine Boeckmann
Executive Digital Editor and Master Gardener
The Old Farmerâs Almanac
GetYourGuidetoGeorgia.com for your window into Georgia celebrations of the wonder of Fall.
