Autumn 2025, specifically referring to astronomical autumn, begins on Monday, September 22, 2025, and concludes on Sunday, December 21, 2025. These dates mark the period defined by the Earth's position in its orbit around the sun.
Understanding Astronomical Autumn
Astronomical seasons are determined by the Earth's tilt and its orbit around the sun, marked by the solstices and equinoxes. Autumn commences with the autumnal (or fall) equinox, a moment when the sun crosses the celestial equator moving southward. This event results in roughly equal day and night across most of the globe. The season then extends until the winter solstice, the shortest day of the year in the Northern Hemisphere.
This method of defining seasons provides a consistent and precise astronomical reference point each year.
Key Dates for Astronomical Autumn
The exact start and end dates for astronomical autumn can shift slightly from year to year due to the Earth's elliptical orbit and the precise timing of the equinoxes and solstices. Below are the dates for recent and upcoming autumn periods, including autumn 2025:
| Year | Autumn Starts | Autumn Ends |
|---|---|---|
| Autumn 2023 | Saturday, 23 September 2023 | Friday, 22 December 2023 |
| Autumn 2024 | Sunday, 22 September 2024 | Saturday, 21 December 2024 |
| Autumn 2025 | Monday, 22 September 2025 | Sunday, 21 December 2025 |
These dates signify the official start and end of the autumn season based on celestial mechanics, providing a global reference for the changing seasons.
