Fall in the Northern Hemisphere starts with the astronomical event called the autumnal equinox. In 2025, this occurs on Monday, September 22, at 18:19 UTC (2:19 PM EDT in Washington DC). This equinox marks the moment when day and night are approximately equal in length. After this day, nights get longer and days get shorter until the winter solstice. Meteorologically, fall typically runs from September to December in the Northern Hemisphere. The timing of fall's start can vary culturally, but the official astronomical start is this equinox date.