America/Santo_Domingo time zone
9:10AMAST
ASTUTC−4+1 h vs New York (you)
No transitions: America/Santo_Domingo stays on AST (UTC−4).
About America/Santo_Domingo
America/Santo_Domingo is the IANA time zone for Dominican Republic. It currently keeps Atlantic Standard Time (AST, UTC−4) all year.
Its principal location is Santo Domingo at 18.47° N, 69.90° W.
Abbreviations in use: AST. Offset page: UTC−4.
Rule for future years (POSIX TZ string)
AST4
The standard time is called AST and is UTC−4. POSIX writes the offset with the opposite sign (west of Greenwich is positive), which is why the string says "4". There is no daylight saving rule: the zone stays on this offset for every year after the end of its explicit transitions. Software that has no full tzdata copy, such as many embedded devices, can use this string directly as the TZ environment variable.
History of America/Santo_Domingo since 1970
The record starts with local mean time (UTC−4:40), which ended on December 31, 1889. The first daylight saving time in the record is in 1966.
| Years | Clocks | Abbreviations |
|---|---|---|
| 1970–1973 | UTC−4:30 in winter, UTC−5 in summer | EST |
| 1974 | UTC−4:30 in winter, UTC−5 in summer; also UTC−4 for part of the year | EST, AST |
| 1975–1999 | UTC−4 all year | AST |
| 2000 | mostly UTC−4; also UTC−5 for part of the year | AST, EST |
| 2001 onward | UTC−4 all year | AST |
Before 1970
4 offset changes before 1970 in the record:
- Saturday, April 1, 1933: UTC−4:40 → UTC−5 (EST)
- Sunday, October 30, 1966: UTC−5 → UTC−4 (EDT), daylight saving time
- Tuesday, February 28, 1967: UTC−4 → UTC−5 (EST)
- Sunday, October 26, 1969: UTC−5 → UTC−4:30, daylight saving time
Changes of the winter (standard) offset: Sunday, October 26, 1969, UTC−5 → UTC−4:30; Sunday, October 27, 1974, UTC−5 → UTC−4.
tzdata commits to accuracy from 1970 for every zone (zone1970.tab); earlier entries are historical research and may be incomplete.
Aliases and zones with the same clock
Other zones that keep exactly the same time under the current rules (but have a different history): America/Barbados, America/Boa_Vista, America/Campo_Grande, America/Caracas, America/Cuiaba, America/Guyana, America/La_Paz, America/Manaus, America/Martinique, America/Porto_Velho, America/Puerto_Rico.
Places on America/Santo_Domingo
Convert Santo Domingo time
Using America/Santo_Domingo in code
Every major platform reads the same IANA ID. Store instants in UTC and convert with the ID at display time; never store a fixed offset for a place that has daylight saving time.
// JavaScript
new Date().toLocaleString('en-US', { timeZone: 'America/Santo_Domingo' })
# Python 3.9+
from zoneinfo import ZoneInfo
from datetime import datetime
datetime.now(ZoneInfo('America/Santo_Domingo'))
// Java
java.time.ZonedDateTime.now(java.time.ZoneId.of("America/Santo_Domingo"))
// Go
loc, _ := time.LoadLocation("America/Santo_Domingo")
time.Now().In(loc)
-- PostgreSQL
SELECT now() AT TIME ZONE 'America/Santo_Domingo';
# Shell
TZ='America/Santo_Domingo' datePlatforms ship their own copy of tzdata and update it on their own schedule. After a rule change, outputs can differ until the platform updates; this page uses tzdata 2026f.