Two ways to define the start of the season
Both dates are valid; they refer to different season systems.
Astronomical Autumn/Fall
Begins at the September equinox, when the Sun crosses the celestial equator.
Meteorological Autumn/Fall
Begins on the fixed calendar date of September 1 in the Northern Hemisphere.
Which date should you use? Use the astronomical date when you mean the solstice- or equinox-based season. Use the meteorological date when you mean the fixed three-month season used for weather and climate records.
When Does Autumn/Fall Start?
Astronomical Autumn/Fall begins on Thursday, September 23, 2027 in the selected timezone. Meteorological Autumn/Fall begins on Wednesday, September 1, 2027. The first follows the astronomical season boundary; the second uses the fixed meteorological calendar.
Season Date & Planning Details
Astronomical Autumn/Fall uses the solstice- or equinox-based seasonal boundary. The meteorological alternative is shown in the comparison above.
This seasonal boundary is not a public holiday.
Astronomical Autumn/Fall Calendar (2026-2035)
| Year | Date | Day | Days Left | Weekend? |
|---|---|---|---|---|
| 2027 | September 23 | Thu | 350 days | No |
| 2028 | September 22 | Fri | 715 days | No |
| 2029 | September 22 | Sat | 1080 days | Yes |
| 2030 | September 22 | Sun | 1445 days | Yes |
| 2031 | September 23 | Tue | 1811 days | No |
| 2032 | September 22 | Wed | 2176 days | No |
| 2033 | September 22 | Thu | 2541 days | No |
| 2034 | September 22 | Fri | 2906 days | No |
| 2035 | September 23 | Sun | 3272 days | Yes |
What is Start of Autumn/Fall?
In the Northern Hemisphere, autumn or fall can begin according to either an astronomical or meteorological definition. The astronomical season starts at the September equinox, a precise moment that can fall on September 22 or 23 depending on the year and time zone. Meteorological autumn uses three complete calendar months and begins every year on September 1.
Calendar note
The astronomical definition is based on Earth’s position in its orbit and the September equinox. The meteorological definition uses fixed three-month seasons, making September 1 the start of autumn for climate records and seasonal statistics in the Northern Hemisphere.
Date variation note
The September equinox happens at one worldwide moment, but its local calendar date can differ by time zone. The astronomical date may also shift between September 22 and September 23 from year to year.
Regional note
These dates describe autumn in the Northern Hemisphere. In the Southern Hemisphere, the September equinox marks the beginning of astronomical spring, while autumn occurs around the March equinox.
Weather note
The calendar start of autumn does not mean cooler weather begins immediately. Local temperatures and seasonal conditions depend on latitude, elevation, climate, and yearly weather patterns.
Frequently Asked Questions
When does autumn start in 2026?
In UTC, astronomical autumn begins at the September equinox on September 23, 2026. Meteorological autumn begins earlier, on September 1, 2026. In some local time zones, the equinox occurs on September 22.
Why are there two dates for the start of fall?
Astronomers define fall by the September equinox, while meteorologists divide the year into fixed three-month seasons and begin fall on September 1.
Are autumn and fall the same season?
Yes. Autumn and fall are two names for the same season. Fall is especially common in American English, while autumn is widely used in British English and internationally.
Does astronomical fall start on the same date every year?
No. The September equinox can fall on September 22 or September 23 in UTC during the years covered here, and the local date can differ by time zone.
Does meteorological fall always start on September 1?
In the Northern Hemisphere, meteorological autumn begins on September 1 each year and runs through November 30.
When does autumn start in the Southern Hemisphere?
Astronomical autumn in the Southern Hemisphere begins around the March equinox. Meteorological autumn there commonly begins on March 1.
More Upcoming Days
The astronomical countdown uses the selected timezone. The meteorological countdown uses its fixed calendar start date in the same timezone.