When does autumn actually begin?

If you ask a meteorologist, autumn sets in when the average temperature drops below 10 degrees Celsius.

When is the first day of fall this year? What to know about the autumn equinox

Environment

What months does each season fall under in the United States? - Quora

The First Day of Fall 2023: All About the Autumn Equinox

When does autumn start? - Met Office

When does autumn start? - Met Office

When does autumn 2023 officially start as equinox marks beginning of new season - Daily Record

Autumn in Japan: 2024 Fall Foliage Forecast

Autumn - Wikipedia