Autumn countdown and date guide
Astronomical autumn (fall) begins in the Northern Hemisphere at the September equinox, when day and night are nearly equal, occurring at a precise instant each year.
Whether you search “how many days until Autumn” or “how many days till Autumn”, both point to the same next date shown above.
What is Autumn?
The first day of autumn is set by the September equinox, when the Sun crosses the celestial equator and day and night are approximately equal in length. Local daylight is not exactly twelve hours because of atmospheric refraction and how sunrise and sunset are defined.
The equinox happens at a single global instant, so the calendar day can be September 22 or 23 depending on your time zone. This page uses the precise UTC instant (from USNO data) and the live countdown converts it to your local time. Meteorological autumn, used by some forecasters, instead starts on September 1.
Why use a Autumn countdown?
A countdown can support seasonal events, outdoor photography, science lessons and planning around rapidly changing daylight.
How people observe it
- Seasonal festivals and harvest events
- Nature walks and photography
- Astronomy education and observation
Planning checklist
- Confirm the local time by converting from UTC
- Check sunset and weather conditions
- Plan seasonal activities for the correct hemisphere
How the date is determined
The first day of astronomical autumn is the September equinox, a precise instant that changes each year. This page uses verified UTC times converted to your local time zone.
Frequently asked questions
When does autumn (fall) start?
Astronomical autumn starts at the September equinox, which falls on September 22 or 23 depending on your time zone. Meteorological autumn, used by some forecasters, begins on September 1.
Is autumn the same as fall?
Yes. “Autumn” and “fall” are two names for the same season; fall is more common in North America and autumn elsewhere.
Are day and night exactly equal?
They are close, but usually not exactly equal because of atmospheric refraction and how sunrise and sunset are defined.
How is the exact start time determined?
This page uses the precise September equinox instant published by the US Naval Observatory (USNO) and converts it to your browser’s local time zone.
Is it autumn everywhere on this date?
No. The September equinox begins autumn in the Northern Hemisphere but spring in the Southern Hemisphere.