09/21/2026
Did you know? This is the last full day of Summer.☀️
Today, Monday, September 21, 2026, is the final full day of astronomical summer in the Northern Hemisphere.
Fall arrives tomorrow at the autumnal equinox, 8:05 p.m. EDT on Tuesday, September 22, the precise moment the Sun crosses the celestial equator heading south. After that instant, nights grow longer than days until the winter solstice in December.