When is the first day of fall

On 22 September 2026, the Northern Hemisphere officially transitions into the autumn season as the autumnal equinox occurs. This astronomical event takes place at 14:44 UTC, marking the precise moment when the sun crosses the celestial equator moving southward. During this time, the Earth experiences a day where the duration of daylight and darkness is nearly equal across the globe. For those living in the Northern Hemisphere, this date signifies the end of summer and the beginning of shorter days and cooler temperatures as the planet tilts away from the sun. Conversely, for the Southern Hemisphere, this date marks the vernal equinox, signaling the start of spring. Meteorologists, however, often define the start of fall by the calendar month, beginning on September 1, but the astronomical arrival remains the most widely recognized marker for the change of seasons. As the leaves begin to change color and temperatures drop, the equinox serves as a celestial reminder of the Earth's ongoing orbit around the sun and the seasonal shifts that follow.