While the answer seems simple, the "correct" month depends entirely on how you define a season. There are three main ways to determine when autumn begins: Astronomical, Meteorological, and Phenological.
There are two main systems used to determine the start and end of autumn: When Do Seasons Start and End? - Time and Date what month is autumn
In most of the Northern Hemisphere, autumn consists of . However, the exact timing depends on whether you follow the calendar or the stars, and which side of the equator you are on. Two Ways to Define the Season While the answer seems simple, the "correct" month
Because the Earth's orbit is not exactly 365 days, the exact date of the equinox shifts slightly each year. While the answer seems simple