Fall officially begins with the autumnal equinox on September 22, 2026, in the Northern Hemisphere — the moment day and night are nearly equal everywhere on Earth.
Key Takeaways
- Astronomical fall: September 22, 2026
- Meteorological fall: September 1 (how climate stats define it)
- After the equinox, days shorten fastest of the whole year
- Clocks do not change until November 1
Why there are two “first days of fall”
Astronomers pin the season to the equinox — the instant the sun crosses the celestial equator heading south. Meteorologists, who need tidy month-long blocks for climate records, define fall as September 1 through November 30. Both are correct; they just serve different purposes. When your weather app says fall started September 1 and your calendar says the 22nd, that is the whole story.
What actually changes after the equinox
- Daylight shrinks at its fastest annual rate — around the equinox, most U.S. cities lose 2–3 minutes of daylight per day
- Equal day and night is approximate: true 12-hour balance lands a few days after the equinox due to how sunrise is measured
- The sun rises due east and sets due west on the equinox — the twice-a-year day your street grid may align perfectly with sunset
- Harvest Moon: the full moon nearest the equinox brings a stretch of bright early-evening moonrises
Dates to anchor the season
| Date | Event |
|---|---|
| Sep 1 | Meteorological fall begins |
| Sep 22 | Autumnal equinox — astronomical fall |
| Nov 1 | Daylight saving time ends (clocks back one hour) |
| Dec 21 | Winter solstice — fall ends |
FAQ
Is the equinox the same day worldwide?
It is the same instant worldwide, but time zones can shift the calendar date — parts of the world may mark it on September 23 local time.
When does fall foliage peak?
Roughly late September in the far north and high elevations, mid-to-late October across much of the U.S. — driven by latitude, elevation, and each year’s weather rather than the equinox itself.
What the equinox looks like where you live
Because the date is astronomical, the experience of it varies with latitude. In the northern tier of the United States and in Canada, the weeks around the equinox bring the steepest drop in daylight, and the shift from summer evenings to early darkness feels sudden. In the southern states the change in day length is gentler, and the more noticeable marker is the first break in summer heat, which often arrives after the equinox rather than on it. Coastal areas lag inland areas because the ocean releases stored summer warmth slowly, which is why September can still feel like summer on the coasts while the interior has clearly turned.
Seasonal changes worth planning around
- Fall foliage: leaf-peeping trips are best booked for late September in northern New England, the Upper Midwest, and the Rockies, and for mid to late October across the Mid-Atlantic and Southeast.
- Hurricane season: the Atlantic season peaks in mid-September and runs through November, so early fall travel to the Gulf and Southeast coasts carries more weather risk than late fall.
- Allergy season: ragweed pollen peaks from late August into early October in much of the country, ahead of the first frost.
- Daylight saving time: clocks fall back on the first Sunday of November, shifting an hour of light from evening to morning.
- Heating season: many utilities move to winter rates in October, making September the practical time to service furnaces and seal drafts.
How the equinox date drifts from year to year
The autumnal equinox falls on September 22 or 23 in the Northern Hemisphere, and occasionally on the 21st or 24th in specific time zones. The drift happens because Earth’s orbit takes about 365.25 days while the calendar uses 365, so the equinox moment slides roughly six hours later each year until a leap year pulls it back. Over the coming decades the equinox will trend slightly earlier in the calendar for North America, which is why September 22 has become the more common date than the 23rd that older references cite.
Is the equinox the same as the first day of school or the start of the fiscal quarter?
No. Those are administrative dates that vary by district and organization. The equinox is the only definition of fall that is fixed by astronomy rather than by convention.
Does the Southern Hemisphere have fall at the same time?
The same moment marks the start of spring south of the equator. Australia, South Africa, and much of South America move toward longer days in late September while the Northern Hemisphere moves toward shorter ones.
Sources
- U.S. Naval Observatory · NOAA
Last updated August 26, 2026 · InfoBrief Staff