ZoneMeetup
Daylight saving: skipped and repeated meeting times
A wall-clock time is not always a unique instant. Time-zone rules can make a local time occur twice—or not occur at all.
Skipped time: no matching instant
When clocks move forward, a range of local times can disappear. Under current New York rules, 02:30 on 8 March 2026 does not occur. Choose another local time; silently shifting it by an hour would change the organizer’s request. ZoneMeetup rejects a nonexistent local time rather than inventing a result.
Repeated time: choose an occurrence
Under current New York rules, 01:30 on 1 November 2026 occurs twice. The earlier occurrence uses UTC−04:00 and corresponds to 05:30 UTC. The later one uses UTC−05:00 and corresponds to 06:30 UTC. Select the intended occurrence before sharing. Tokyo sees the later instant at 15:30 on 1 November.
Not every change is one hour
Australia/Lord_Howe uses a half-hour seasonal change. Other places have half-hour or quarter-hour offsets without the same seasonal pattern. The elapsed length of a local date can differ from 24 hours. Never derive timezone rules by adding a fixed number of whole hours to a country name.
Local recurrence and UTC recurrence differ
A weekly 09:00 organizer-local meeting can change its UTC start after a transition. A fixed-UTC series can change the organizer’s wall-clock time instead. Participants in different regions may change clocks on different dates, creating several weeks of a different meeting time. Preview the full series and read each local date, offset and conflict before exporting.
Rules are data, and data can age
ZoneMeetup calculates with the timezone rules supplied by your browser/OS through Temporal and Intl. Its source page compares selected offsets with samples compiled from IANA 2026e. A mismatch warns that runtime rules differ; a match does not prove that every transition is covered. The checker does not patch your browser.
Update your browser and OS and verify important future times with participants. An already downloaded ICS file contains fixed instants and will not automatically regenerate after a legal timezone change.
A short verification checklist
- Use a named IANA zone and a full calendar date.
- Resolve any skipped or repeated clock warning.
- Read the local start and end date for every participant.
- Preview recurring dates across transitions.
- Check the source warning and then share the selected instant.
Create an event-time link · Check source rules · Plan a fair meeting. Authoritative source: IANA Time Zone Database.