When Does Antarctica Experience Equal Day and Night?

Antarctica has the shortest days and nights—meaning equal lengths of daylight and darkness—during the spring and autumn equinoxes, which occur around September 22–23 and March 20–21 each year.

During these equinoxes, the Sun rises and sets at nearly the same time everywhere on Earth, giving every location, including Antarctica, approximately 12 hours of day and 12 hours of night.