Days Until Fall Calculator
Enter your start date and hemisphere to find exactly how many days, weeks, and hours remain until the next autumnal equinox. The calculator works for both the Northern Hemisphere (September equinox) and Southern Hemisphere (March equinox), and it updates automatically when you change any input.
What marks the start of fall?
Fall (also called autumn) begins at the autumnal equinox, the moment when the Sun crosses the celestial equator moving southward. At that instant, day and night are nearly equal in length everywhere on Earth. In the Northern Hemisphere, the equinox falls around September 22 or 23. In the Southern Hemisphere, it falls around March 20 or 21 - the same astronomical event, just experienced as the opposite season.
Why does the equinox date shift from year to year?
The autumnal equinox is not on the same calendar date every year because a solar year is about 365.25 days, not exactly 365. Leap years add an extra day every four years to keep the calendar aligned with Earth's orbit, which causes the equinox to drift by one or two days over a four-year cycle. The date can also shift slightly depending on your timezone, because the equinox is a precise astronomical moment that falls at different local times around the world. Over the 2024-2030 period, the Northern Hemisphere equinox falls between September 22 and September 23.
How to calculate days until fall manually
To count the days from any date to the fall equinox, first look up the equinox date for the target year using an official source such as the U.S. Naval Observatory or timeanddate.com. Then subtract your start date from the equinox date using simple date arithmetic. If your start date is June 19 and the equinox is September 23, there are 12 days left in June (30 minus 19 minus 1 for the start day itself), plus 31 days in July, 31 in August, and 23 in September - giving 12 + 31 + 31 + 23 = 97 days. This calculator performs that arithmetic automatically for any date you enter.
How long does fall last?
In the Northern Hemisphere, fall runs from the September equinox to the December solstice (around December 21), a span of roughly 88 to 90 days depending on the year. In the Southern Hemisphere, fall runs from the March equinox to the June solstice (around June 21), a similar span. Fall is the second shortest season of the year on average - only spring is shorter - because Earth moves slightly faster in its orbit during the Northern Hemisphere winter, so those seasons pass more quickly.
Autumnal equinox dates (2024-2030)
| Year | Northern Hemisphere (Sep) | Southern Hemisphere (Mar) |
|---|---|---|
| 2024 | Sep 22 | Mar 20 |
| 2025 | Sep 22 | Mar 20 |
| 2026 | Sep 23 | Mar 20 |
| 2027 | Sep 23 | Mar 20 |
| 2028 | Sep 22 | Mar 20 |
| 2029 | Sep 22 | Mar 20 |
| 2030 | Sep 23 | Mar 20 |
Approximate dates for both hemispheres. Exact times vary by a few hours depending on timezone.
Frequently asked questions
What day does fall start in 2026?
In the Northern Hemisphere, fall 2026 begins on September 23 at the autumnal equinox. The exact time depends on your timezone, but for calendar purposes September 23 is the first day of fall in 2026.
Is the first day of fall always September 22 or 23?
For the Northern Hemisphere, yes - the autumnal equinox falls on September 22 or September 23 between 2024 and 2030. The exact date depends on the year and shifts slightly due to the 365.25-day solar year. Occasionally, rare calendar alignments can push it to September 21 or 24, but that is uncommon.
What is the difference between meteorological and astronomical fall?
Meteorological fall is defined as September, October, and November (in the Northern Hemisphere) for convenience in climate record-keeping, so it always starts on September 1. Astronomical fall, which this calculator uses, starts at the autumnal equinox - usually September 22 or 23 - and ends at the December solstice around December 21. The two differ by about three weeks at the start and by a day or two at the end.
When does fall start in the Southern Hemisphere?
In the Southern Hemisphere, fall begins at the March equinox - around March 20 - and ends at the June solstice around June 21. This is because the seasons are opposite: when it is fall in the Northern Hemisphere (September), it is spring in the Southern Hemisphere.
How many hours until fall?
Multiply the number of days until fall by 24 to get the approximate number of hours. For example, if there are 96 days until the equinox, that is 96 x 24 = 2,304 hours. This calculator displays both figures automatically. For a live seconds-precise countdown, the result will change slightly as hours tick by.
Why do day and night become equal on the equinox?
At the equinox, the Earth's axis is tilted neither toward nor away from the Sun. The Sun appears to cross the celestial equator - the projection of Earth's equator into space - and at that moment every location on Earth receives roughly equal amounts of sunlight and darkness. In practice, atmospheric refraction and the finite diameter of the Sun mean sunrise and sunset times are not perfectly equal, but they are as close to equal as they get all year.