If you aren't looking at a calendar, you might determine the start of autumn through —the study of periodic biological phenomena. This is "nature’s autumn," and its timing varies based on your specific climate and latitude. Signs include:
The arrival of autumn is one of the most anticipated transitions of the year. It is a season romanticized in poetry and art for its golden light, crisp air, and the melancholic beauty of decay. Yet, if one were to ask, "When is autumn?" the answer is surprisingly complex. There is rarely a single when is autumn
In the Northern Hemisphere, autumn typically spans the months of . In the Southern Hemisphere (like Australia or Brazil), the seasons are flipped, and autumn occurs during March, April, and May . 1. Astronomical Autumn (The Equinox) If you aren't looking at a calendar, you
Autumn begins on March 1 and ends on May 31 . It is a season romanticized in poetry and
. This is the exact moment when the sun crosses the celestial equator, making day and night nearly equal in length. Northern Hemisphere (2026): Tuesday, September 22, at 8:04 P.M. EDT. Southern Hemisphere (2026): Friday, March 20, at 14:46 UTC. Why it moves: Because the Earth’s orbit isn't a perfect circle and takes roughly 365.25 days, the equinox date can shift between September 21, 22, or 23 from year to year. 2. The Meteorological Answer: By the Calendar If you prefer a tidier schedule, you’re likely on "Team Meteorological." Meteorologists and climatologists divide the year into four equal three-month periods to make record-keeping and data comparison easier. Northern Hemisphere: September 1 to November 30. Southern Hemisphere: March 1 to May 31. The logic: This system aligns better with "calendar months" and captures the three-month transition period when temperatures typically drop before the deep cold of winter. 10 sites The difference between meteorological and astronomical ... Feb 19, 2025 —