Time zone · Americas
AST
Atlantic Standard Time
Atlantic Standard Time (AST, UTC−04:00) covers a broad swath of the Caribbean and parts of eastern Canada, where most islands stay on a steady year-round clock while a handful of Canadian zones shift forward in summer—making AST a mix of tropical consistency and northern-seasonal change.
Friday, June 5, 2026
Current offset
UTC-04:00
Standard · AST
Daylight saving
Not observed
Year-round standard time
IANA zones
23
None observe daylight saving
DST offset
—
No summer variant
About AST
A fixed, year-round offset.
Atlantic Standard Time (AST, UTC−04:00) covers a broad swath of the Caribbean and parts of eastern Canada, where most islands stay on a steady year-round clock while a handful of Canadian zones shift forward in summer—making AST a mix of tropical consistency and northern-seasonal change.
IANA zones · the technical identifiers
The 23 zones that resolve to AST.
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 AST
The same hour, city by city.
25 cities · all UTC-04:00
Where AST is used
23 countries.
Same offset · UTC-04:00
Other zones at UTC-04:00 right now.
These named zones share AST's offset today. When daylight saving rules differ, they drift apart for part of the year.
Frequently asked questions
Common questions about AST, daylight saving, and how to handle it in software. Can't find what you need? Email [email protected].
- Why do most AST zones never change their clocks?
- Most Caribbean islands near the equator see very little variation in daylight throughout the year, so they keep a fixed offset (UTC−04:00) and skip daylight saving entirely.
- Which AST areas do observe daylight saving?
- A few Canadian zones—like parts of Nova Scotia and Quebec—follow Atlantic Daylight Time (ADT, UTC−03:00) in summer, shifting clocks forward by one hour.
- How many time zones share the AST code?
- There are 29 member zones under the AST umbrella, spanning independent nations, overseas territories, and Canadian provinces.
- Is AST the same as Eastern Standard Time?
- No. AST is one hour ahead of EST (UTC−05:00) and aligns with EDT (UTC−04:00) only when Eastern Time is observing daylight saving.
- Why does Anguilla never observe DST?
- Anguilla’s location in the Caribbean means nearly equal day and night year-round, so there’s little benefit to shifting clocks.
- What’s the historical origin of AST?
- AST was formalized in the early 20th century to standardize timekeeping across the Atlantic-facing Caribbean and parts of eastern Canada.
- Do all AST countries share the same date for time changes?
- No. Only the Canadian zones that observe DST follow North American daylight saving schedules; the rest stay fixed.
- How does AST affect travel between islands?
- Travel between most AST islands doesn’t require clock adjustments, but flying to or from Canadian AST zones in summer means a one-hour shift.
- Why is AST important for global business?
- AST links Caribbean financial hubs and eastern Canadian markets, offering a stable time reference for cross-regional coordination.
Free · Developer API
Time, as JSON.
Every IANA time zone with live offsets, DST status, and the countries and cities that use them — clean, dependable JSON. Sign up free and get an API key in seconds.
countries, cities, convert, DST transitions coming next.
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