When does autumn 2026 begin? The September equinox falls Tuesday, September 22 — astronomical fall in the Northern Hemisphere.
Current target date: Tuesday, September 22, 2026 (Autumn equinox). Calendar anchors follow public observance — your school district or country may use a different day.
Astronomical fall 2026 begins with the September equinox on Tuesday, September 22. Meteorologists already call September 1 "meteorological fall" for record-keeping — pumpkin spice does not wait for the sun's position. Southern Hemisphere readers flip the season; this page tracks northern autumn.
Autumn equinox
Tuesday, September 22, 2026
Astronomical fall starts at an instant — the equinox — not when the first leaf drops
The September equinox is the moment the Sun crosses the celestial equator heading south. In 2026 that event falls on Tuesday, September 22 for most US calendars. Weather can still feel like late summer that afternoon; the label is orbital geometry, not a thermostat reading.
Meteorologists already called it autumn on September 1
Climate records prefer meteorological seasons: autumn as September–October–November. That keeps months whole for statistics. Pumpkin-spice marketing follows the meteorological vibe more than the equinox — which is why “first day of fall” arguments online talk past each other.
This page is Northern Hemisphere autumn — south of the equator it’s spring
The same equinox that starts northern fall starts southern spring. If you landed here from Sydney or Buenos Aires searching “first day of fall,” you want the March equinox page for southern autumn, not September 22.
"Equal day and night" often isn't exactly on equinox day where you live
Atmosphere bends sunlight, and “sunrise/sunset” are defined when the Sun’s disc is a bit below the geometric horizon — so the date with closest 12-hour day (equilux) can miss the equinox by a day or two depending on latitude. September 22, 2026 is still the astronomical season change; it is not a promise that your city’s daylight minutes hit exactly 12:00:00 that calendar day.
Frequently asked questions
Quick answers about this release date.
1Is September 22 the only "first day of fall"?
For astronomy in the Northern Hemisphere, fall begins at the September equinox — in 2026 that calendar date is September 22. Meteorologists often call September 1 the start of meteorological autumn for tidy monthly stats. Both definitions are used; they answer different questions.
2Does fall start the same day in Australia?
No. In the Southern Hemisphere the September equinox begins astronomical spring. This page tracks Northern autumn; flip the season if you are south of the equator.
3Does the equinox mean day and night are exactly equal?
Almost — equal day and night is closer to the related equilux, which can differ by a day or two by latitude because of refraction and how sunrise/sunset are defined. The equinox itself is the moment the Sun crosses the celestial equator.
4Why does the equinox date flip between September 22 and 23?
Earth’s orbit and the leap-year cycle nudge the exact UTC moment across calendar boundaries. Some years the civil date is the 22nd in US time zones, sometimes the 23rd — 2026’s commonly listed Northern autumn start is September 22.
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