AST — Atlantic or Arabia Standard Time
AST is ambiguous: it stands for 2 different times, both in use today. When a message says “AST”, the sender’s country usually tells you which one is meant; to be safe, write the UTC offset (for example AST = UTC−4 or AST = UTC+3).
- Atlantic Standard Time · UTC−4 · Atlantic Canada and the Caribbean
- Arabia Standard Time · UTC+3 · Arabian Peninsula and Iraq
Atlantic Standard Time
AST stands for Atlantic Standard Time, UTC−4, 4 hours behind UTC. It is used in Atlantic Canada and the Caribbean: in winter in Canada, and all year in Puerto Rico, the Dominican Republic, Barbados and Trinidad and Tobago.
Countries and territories: Canada, Puerto Rico, Dominican Republic, Barbados and Trinidad and Tobago.
Zones: America/Halifax, America/Puerto_Rico, America/Santo_Domingo, America/Barbados, America/Port_of_Spain.
Arabia Standard Time
AST stands for Arabia Standard Time, UTC+3, 3 hours ahead of UTC. It is used all year in Arabian Peninsula and Iraq.
Countries and territories: Saudi Arabia, Iraq, Kuwait, Qatar, Bahrain and Yemen.
Zones: Asia/Riyadh, Asia/Baghdad, Asia/Kuwait, Asia/Qatar, Asia/Bahrain, Asia/Aden.