Argentina is located at a longitude that would naturally put it in the UTC−04:00 or UTC−05:00 time zone; however, it actually uses the UTC−03:00 time zone. Argentina determines whether to change clocks in observation of daylight saving time on a year-by-year basis, and individual provinces may opt out of the federal decision. At present, Argentina does not change clocks.[ citation needed ]
The Argentine Hydrographic Service [1] maintains the official national time.
The first official standardization of time in Argentina took place on 31 October 1894, with establishment of UTC−04:00 as the nation's standard time. [2] From 1920 to 1969, the official time switched biannually between UTC−04:00 as standard time in winter and UTC−03:00 as daylight saving time in summer. [3] From 1974 to 1993, clocks advanced again, such that the official time switched biannually between UTC−03:00 as winter DST and UTC−02:00 as summer double DST. [4] In 1993, the national time was fixed at UTC−03:00, called Argentina Time (ART; [5] [6] Spanish : hora oficial argentina, HOA). In 2007 and 2008, biannual switching between UTC–3:00 (winter DST) and UTC–2:00 (summer DST) resumed; in 2009, this was replaced again with year-round UTC–3:00 (permanent DST). [7]
In the file zone.tab of the IANA time zone database Argentina has the following zones:
| From 12:00 AM of the day | Adopted Time Zone | Until 11:59 of the day |
|---|---|---|
| 01-05-1920 | -4 | 30-11-1930 |
| 01-12-1930 | -3 | 31-03-1931 |
| 01-04-1931 | -4 | 14-10-1931 |
| 15-10-1931 | -3 | 29-02-1932 |
| 01-03-1932 | -4 | 31-10-1932 |
| 01-11-1932 | -3 | 29-02-1933 |
| 01-03-1933 | -4 | 31-10-1933 |
| 01-11-1933 | -3 | 28-02-1934 |
| 01-03-1934 | -4 | 31-10-1934 |
| 01-11-1934 | -3 | 28-02-1935 |
| 01-03-1935 | -4 | 31-10-1935 |
| 01-11-1935 | -3 | 29-02-1936 |
| 01-03-1936 | -4 | 31-10-1936 |
| 01-11-1936 | -3 | 28-02-1937 |
| 01-03-1937 | -4 | 31-10-1937 |
| 01-11-1937 | -3 | 28-02-1938 |
| 01-03-1938 | -4 | 31-10-1938 |
| 01-11-1938 | -3 | 28-02-1939 |
| 01-03-1939 | -4 | 31-10-1939 |
| 01-11-1939 | -3 | 29-02-1940 |
| 01-03-1940 | -4 | 30-06-1940 |
| 01-07-1940 | -3 | 14-06-1941 |
| 15-06-1941 | -4 | 14-10-1941 |
| 15-10-1941 | -3 | 31-07-1943 |
| 01-08-1943 | -4 | 14-10-1943 |
| 15-10-1943 | -3 | 28-02-1946 |
| 01-03-1946 | -4 | 30-09-1946 |
| 01-10-1946 | -3 | 30-09-1963 |
| 01-10-1963 | -4 | 14-12-1963 |
| 15-12-1963 | -3 | 29-02-1964 |
| 01-03-1964 | -4 | 14-10-1964 |
| 15-10-1964 | -3 | 28-02-1965 |
| 01-03-1965 | -4 | 14-10-1965 |
| 15-10-1965 | -3 | 28-02-1966 |
| 01-03-1966 | -4 | 14-10-1966 |
| 15-10-1966 | -3 | 01-04-1967 |
| 02-04-1967 | -4 | 30-09-1967 |
| 01-10-1967 | -3 | 06-04-1968 |
| 07-04-1968 | -4 | 05-10-1968 |
| 06-10-1968 | -3 | 05-04-1969 |
| 06-04-1969 | -4 | 04-10-1969 |
| 05-10-1969 | -3 | 22-01-1974 |
| 23-01-1974 | -2 | 30-04-1974 |
| 01-05-1974 | -3 | 30-11-1988 |
| 01-12-1988 | -2 | 04-03-1989 |
| 05-03-1989 | -3 | 14-10-1989 |
| 15-10-1989 | -2 | 03-03-1990 |
| 04-03-1990 | -3 | 20-10-1990 |
| 21-10-1990 | -2 | 02-03-1991 |
| 03-03-1991 | -3 | 19-10-1991 |
| 20-10-1991 | -2 | 29-02-1992 |
| 01-03-1992 | -3 | 17-10-1992 |
| 18-10-1992 | -2 | 06-03-1993 |
| 07-03-1993 | -3 | 29-12-2007 |
| 30-12-2007 | -2 | 15-03-2008 |
| 16-03-2008 | -3 | 18-10-2008 |
| 19-10-2008 | -2 | 14-03-2009 |
| 15-03-2009 | -3 | -present |
 | This article about a location in Argentina is a stub. You can help Wikipedia by expanding it. |
 | This standards- or measurement-related article is a stub. You can help Wikipedia by expanding it. |