World clocks & live time
DST transition tracker
Never be caught out by a clock change. Add the cities you care about and see exactly when each one next springs forward or falls back — with the new offset.
Transitions are found by scanning each zone's real offset forward from today, so they reflect the current daylight-saving rules.
How to use the dst transition tracker
Add the cities you work across
Each one is tracked independently, because daylight saving is decided per zone and not per country — Arizona and Colorado sit in the same country and behave differently.
Read the next transition
For every city you get the exact date and local time its clocks next move, the direction they move, and the offset they land on.
Spot the weeks that break
Compare the transition dates. Where two cities change on different days, the offset between them is temporarily different from its usual value — those are the weeks recurring meetings drift.
Confirm the zones that never change
Cities on a fixed offset are marked as having no change coming. Most of Asia and Africa, and a growing number of other places, sit permanently on one offset.
Why daylight saving breaks recurring meetings
The offset between two cities is not a property of the pair — it is the difference between two independent functions of the date. New York and London are normally five hours apart, but they change their clocks on different weekends: the United States moves on the second Sunday of March, the European Union on the last Sunday of that month. For those two or three weeks the gap is four hours, and every recurring call between them lands an hour off.
The southern hemisphere makes it worse, because it moves the opposite way. Between Europe and Australia the offset swings by two full hours across the year, and there are short windows where both are mid-transition. Any assumption of the form "Sydney is always nine hours ahead" is wrong for a meaningful fraction of the year.
The rules themselves are not stable either. Governments change them, sometimes with a few weeks' notice: Chile, Iran, Mexico, Jordan, Syria and others have all moved, abolished or reinstated daylight saving in recent years. This is why the IANA time zone database is versioned and updated several times a year, and why hard-coding an offset in an application is a bug waiting for a news cycle.
The transitions here are found by walking each zone's real offset forward day by day and then binary-searching the boundary down to the second, using the zone database in your browser. That means the answers reflect whatever rules are currently in force, including changes announced since the tool was written.
When you'd reach for it
Protecting a recurring standup
Find the weeks where a fixed weekly call will shift, and warn the team before it does.
Release and maintenance windows
Avoid scheduling a deploy across a transition, where a wall-clock hour repeats or vanishes entirely.
Payroll and shift rotas
Night shifts spanning a transition are 23 or 25 hours long, which affects both pay and coverage.
Travel booking
Check whether your destination changes its clocks during the trip.
Contract and SLA deadlines
Confirm that a deadline expressed in local time means what both parties think it does.
Debugging a scheduler
Confirm whether a job that fired an hour early was a bug or the correct handling of a real transition.
Questions & answers
- How does it find the next change?
- It reads each zone's real UTC offset and scans forward day by day until the offset shifts, then narrows in on the moment — so it always reflects the current daylight-saving rules.
- Why do some cities show no change?
- Many places don't observe daylight saving — most of Asia, and regions like Arizona — so their offset is stable all year and no upcoming transition is shown.
- Which direction is 'forward' vs 'back'?
- Forward (spring) moves the clock ahead and increases the UTC offset; back (autumn) moves it behind. The card shows the new offset either way.