Fall in 2025 begins on Monday, September 22, 2025, in the Northern Hemisphere. This date corresponds to the autumnal equinox, which marks the official start of fall. The fall season then ends on Sunday, December 21, 2025, at the winter solstice. In the Southern Hemisphere, the fall season for 2025 occurred earlier, starting on March 20, 2025, and the next fall will begin there on March 20, 2026. The start of fall varies slightly based on astronomical definitions (equinoxes and solstices) and meteorological definitions (fixed calendar dates, with fall starting on September 1). The astronomical definition is commonly used and marks the moment the sun crosses the celestial equator, giving nearly equal day and night. For 2025, the exact autumnal equinox falls on September 22 at 18:19 UTC. Thus, for most of the Northern Hemisphere in 2025, fall begins on September 22.