Overview

• The equinox occurs on Monday, 22 September 2025 at roughly 18:19–18:20 UTC, which is 12:19–12:20 in Mexico City and 15:19 in Argentina, according to UNAM and national observatories.
• In the United States, the moment converts to 2:20 p.m. ET, 1:20 p.m. CT, 12:20 p.m. MT and 11:20 a.m. PT, based on published time-zone guidance.
• Mexico’s culture ministry and INAH have organized visitor operations at Chichén Itzá to manage crowds for the light-and-shadow display on the Pyramid of Kukulkán.
• Autumn in the northern hemisphere will last about 89 days and 21 hours, ending with the winter solstice on 21 December, per observatory data.
• Reports note minor discrepancies in some local listings, with observatories advising use of official timings and recommending shadow tracking as a practical way to perceive the event.