When does autumn start?
If you are asking when does autumn start, the useful answer is a practical timing range plus the one source or warning sign that can change it. Sky dates move with location, time zone, and yearly calendars, so check a current astronomy source when precision matters.
Short answer
Autumn usually starts around September 22 or 23 by the astronomical calendar in the Northern Hemisphere.
Detailed answer
Use the short answer as a starting point, then adjust for your location, condition, device, recipe, schedule, or official source. When accuracy matters, check the current primary source rather than an old screenshot or copied post.
Practical notes
Keep a reminder, compare conditions, and re-check the source when timing can change. For food, health-like, safety, and official schedule questions, choose caution over convenience.
What to watch out for
Use the same calendar type when comparing dates.
Related questions
This page is general information. Dates, platform rules, safety guidance, and official schedules can change.