This article has been updated to include new details.

Farewell to flip-flops and welcome back pumpkin spice.

Our long, hot summer concludes on Sunday at 8:48 a.m. EDT with the arrival of the autumnal equinox, signaling the start of fall in the Northern Hemisphere.

Each September, typically on the 22nd or 23rd, the sun is positioned directly over the equator, indicating the autumnal equinox for those in the Northern Hemisphere.

Conversely, in the Southern Hemisphere, this event is known as the vernal or spring equinox, marking the onset of spring.

What happens to the Earth during the autumnal equinox

At the autumnal equinox, the Earth’s tilt is balanced so that it is neither leaning toward nor away from the sun, leading to approximately equal amounts of day and night across all locations, as per the National Weather Service.

The term “equinox” originates from the Latin words “aequalis” meaning “equal” and “nox” meaning “night.” On both the autumnal and spring equinoxes, most regions experience around 12 hours of daylight and 12 hours of night.

Seasons explained by the Earth’s tilt

The Earth’s seasons result from its tilted axis, which is angled at 23.5 degrees in relation to its orbital path. As Earth orbits the sun, its axis remains pointed in the same direction. On September 22, daytime and nighttime durations are nearly equal.

What occurs to daylight after the autumnal equinox?

Following the equinox, for the next three months until the winter solstice in December, the duration of daylight will gradually decrease each day.

The fall equinox brings several impacts, including:

• Agricultural implications: Farmers harvest crops in line with the fall equinox, which traditionally marks the start of the harvest season to ensure food is stored for winter.
• Changes in animal activities: To prepare for the colder months, many animal species alter their feeding habits or migrate due to the changing light during the equinox.
• Effects on human well-being: Variations in daylight can disrupt our biological circadian rhythm, impacting our sleep and emotional well-being. Some individuals may experience Seasonal Affective Disorder (SAD).

SOURCE NASA, National Weather Service, NOAA, HowStuffWorks.com, and Sciencefocus.com