Time zone · Americas
ADT
Atlantic Daylight Time
Atlantic Daylight Time (ADT) unites parts of eastern Canada, Greenland’s remote Thule, and Bermuda under a shared warm-hour rhythm that stretches evening light across the North Atlantic.
Sunday, May 31, 2026
Current offset
UTC-03:00
Daylight · ADT
Daylight saving
Active
Reverts 1 Nov 2026
IANA zones
6
6 observe DST, 0 don't
DST offset
—
No summer variant
About ADT
Standard time, with a summer shift.
Atlantic Daylight Time (ADT) unites parts of eastern Canada, Greenland’s remote Thule, and Bermuda under a shared warm-hour rhythm that stretches evening light across the North Atlantic.
IANA zones · the technical identifiers
The 6 zones that resolve to ADT.
For software, always store the IANA identifier — never the abbreviation alone. The database keeps these zones distinct because their rules can, and historically did, diverge.
Cities currently on ADT
The same hour, city by city.
1 city · all UTC-03:00
Where ADT is used
3 countries.
Same offset · UTC-03:00
Other zones at UTC-03:00 right now.
These named zones share ADT's offset today. When daylight saving rules differ, they drift apart for part of the year.
Frequently asked questions
Common questions about ADT, daylight saving, and how to handle it in software. Can't find what you need? Email [email protected].
- Which countries currently observe ADT?
- ADT covers regions in Canada (eastern provinces like Nova Scotia and New Brunswick), Greenland (Thule Air Base), and Bermuda during daylight saving time.
- When does ADT take effect each year?
- ADT is active from the second Sunday in March until the first Sunday in November—this period aligns with most other North American daylight saving transitions.
- Does every member zone follow daylight saving time?
- Yes, all six member zones observe DST and are currently operating on ADT, making synchronization seamless across the region.
- What happens when ADT ends?
- On November 1st, clocks fall back to Atlantic Standard Time (AST), returning to UTC-04:00 and shorter winter days.
- Is ADT unique compared to other North American time zones?
- While aligned with U.S. Eastern Time 1 leg ahead in daylight terms, ADT is distinctive for spanning such a wide geographic area—including Arctic Canada and subtropical Bermuda—under one shared offset.
- How does living on ADT affect daily life in Halifax?
- Residents enjoy extended evening daylight through summer, supporting outdoor activities and aligning closely with business hours in major Canadian and U.S. markets.
- Where in Greenland uses ADT?
- Only Thule Air Base follows ADT; most of Greenland uses a different time zone system, making Thule an outlier tied more closely to North Atlantic timing.
- Why is Bermuda in the ADT region?
- Bermuda adopted ADT in 1974 to align its clocks with nearby North American markets, strengthening economic and communication ties despite its mid-Atlantic location.
- Can travelers expect uniform time across all ADT zones right now?
- Absolutely—all six member zones are currently synchronized on UTC-03:00, so no internal time differences occur within the region until November.
Free · Developer API
Time, as JSON.
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