AST — Atlantic Standard Time
UTC-4 / ADT during DST
Current AST Time
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America/Halifax
Atlantic Standard Time (AST) is 4 hours behind Coordinated Universal Time (UTC-4). It is used in eastern Canada and parts of the Caribbean. During daylight saving time, the region switches to Atlantic Daylight Time (ADT, UTC-3).
AST Key Facts
- Full name: Atlantic Standard Time
- Abbreviation: AST
- UTC offset: UTC-4
- DST: Switches to ADT (UTC-3) during summer
- IANA identifier: America/Halifax
- Countries: Canada, Puerto Rico, US Virgin Islands
- Major cities: Halifax, San Juan
Understanding AST
Atlantic Standard Time (AST) uses a UTC offset of UTC-4, placing it 4 hours behind UTC. During Daylight Saving Time, the region shifts to ADT (UTC-3), moving clocks forward by one hour.
AST is observed across 3 countries, including Canada, Puerto Rico, US Virgin Islands. Major metropolitan areas in this time zone include Halifax, San Juan, making it one of the most commercially active time zones in the world.
Frequently Asked Questions
What is AST time?
AST stands for Atlantic Standard Time. It is UTC-4, meaning it is 4 hours behind Coordinated Universal Time (UTC).
What countries use AST?
AST (Atlantic Standard Time) is used in Canada, Puerto Rico, US Virgin Islands. Major cities in this timezone include Halifax, San Juan.
Does AST observe Daylight Saving Time?
Yes, AST observes Daylight Saving Time. During DST, clocks move forward by 1 hour to ADT (UTC-3). The exact dates vary by country.
What is the UTC offset for AST?
AST has a UTC offset of UTC-4. During Daylight Saving Time, it shifts to ADT with a UTC offset of UTC-3. The IANA time zone identifier is America/Halifax.
What is AST in military time?
In the military time zone system, AST (UTC-4) is designated with a specific letter code. Military time zones use letters A through Z (excluding J) to represent offsets from UTC.