Astronomical
Follows Earth’s journey around the Sun, so the precise moment shifts slightly each year.
A season with two birthdays
When does autumn start?
It depends on how you count. Astronomical autumn begins at the September equinox in the Northern Hemisphere and the March equinox in the Southern Hemisphere. Meteorological autumn begins on the first day of September or March, respectively.
Meteorological
Uses tidy three-month blocks, making weather and climate records easier to compare.
Save the date
Upcoming autumn dates
When astronomical dates are selected, the table uses UTC and the live answer compares the same instant in your local time. Meteorological dates begin at midnight in your local time.
| Year | Date | Time (UTC) |
|---|---|---|
| Loading dates… | ||
Good questions
Autumn, in a nutshell
What is the autumn equinox?
It is the instant the Sun crosses the celestial equator. Day and night are close to equal in length, though not perfectly equal because of the Sun’s apparent size and atmospheric refraction.
Why are there two autumn start dates?
Astronomical seasons describe Earth’s orbit; meteorological seasons group the year into four consistent three-month periods. Both definitions are useful, just for different jobs.
Are fall and autumn the same thing?
Yes. “Fall” is especially common in North American English, while “autumn” is more common in British English. They name the same season.
How long does autumn last?
Meteorological autumn is always three complete calendar months. Astronomical autumn runs from the autumn equinox to the winter solstice—roughly 89 to 90 days, with a small variation from year to year.
When does winter start?
Astronomical winter begins at the winter solstice: in December in the north and June in the south. Meteorological winter starts on 1 December in the north and 1 June in the south. During autumn, the live timer above counts down to it.