Historically distinct IANA time zone
Atlantic/Azores
Local time now
+00 · current offset
- Countries
- Portugal
- GPS reference
- 37.73° N, 25.67° W
- Data source
- IANA europe
- Aliases
- None
PortugalAzores
Geographic context
Where this clock belongs
The map marks the IANA reference location and associated country, not a time-zone boundary.
GPS reference: 37.73° N, 25.67° W. Associated countries: PT.
The Wikipedia link provides additional context; it is not evidence for a historical claim. Transition data comes from the IANA source file.
Notes from the time database
The story behind the clock
These source notes describe a period or rule. They do not, by themselves, establish a causal claim for a particular clock change.
Decreto 1469 of 1915-03-30 ... had nothing to do with DST; rather it regulated the sending of time signals. But we do see linkage to Spain in the 1920s below. According to the Observatory, standard time was first advanced by Decreto 2433 of 1916-06-09 and restored by Decreto 2712 of 1916-10-28. While Whitman gives 1916-10-31 for the latter transition, Shanks & Pottenger agrees more closely with the decree, which stated that its provision "will start sixty minutes after the end of 31 October, according to the current time," i.e., 01:00 on 1 November.
Midsummer
The following rules are for the European Union and for its predecessor organization, the European Communities. For brevity they are called "EU rules" elsewhere in this file.
Original IANA source file: europe.
Civil-time record
Recorded changes over time
From 1883 to 2027 · 196 recorded transitions
Recurring daylight-saving changes are grouped separately when JavaScript is available.
Notable changes
One-off changes and transitions outside the recurring seasonal rhythm.
- -01:54 · HMTStandard time applies
- -02:00 · -02Standard time applies
- -01:00 · -01Daylight saving time begins
- -02:00 · -02Standard time applies
- -01:00 · -01Daylight saving time begins
- -02:00 · -02Standard time applies
Browse every recorded transition
| Local time after transition | Offset after | Abbreviation | Rule |
|---|---|---|---|
| 1883-12-31 23:48 | -01:54 | HMT | Standard time |
| 1912-01-01 00:00 | -02:00 | -02 | Standard time |
| 1916-06-18 00:00 | -01:00 | -01 | Daylight saving time |
| 1916-11-01 00:00 | -02:00 | -02 | Standard time |
| 1917-03-01 01:00 | -01:00 | -01 | Daylight saving time |
| 1917-10-14 23:00 | -02:00 | -02 | Standard time |
| 1918-03-01 01:00 | -01:00 | -01 | Daylight saving time |
| 1918-10-14 23:00 | -02:00 | -02 | Standard time |
| 1919-03-01 01:00 | -01:00 | -01 | Daylight saving time |
| 1919-10-14 23:00 | -02:00 | -02 | Standard time |
| 1920-03-01 01:00 | -01:00 | -01 | Daylight saving time |
| 1920-10-14 23:00 | -02:00 | -02 | Standard time |
| 1921-03-01 01:00 | -01:00 | -01 | Daylight saving time |
| 1921-10-14 23:00 | -02:00 | -02 | Standard time |
| 1924-04-17 00:00 | -01:00 | -01 | Daylight saving time |
| 1924-10-04 23:00 | -02:00 | -02 | Standard time |
| 1926-04-18 00:00 | -01:00 | -01 | Daylight saving time |
| 1926-10-02 23:00 | -02:00 | -02 | Standard time |
| 1927-04-10 00:00 | -01:00 | -01 | Daylight saving time |
| 1927-10-01 23:00 | -02:00 | -02 | Standard time |
| 1928-04-15 00:00 | -01:00 | -01 | Daylight saving time |
| 1928-10-06 23:00 | -02:00 | -02 | Standard time |
| 1929-04-21 00:00 | -01:00 | -01 | Daylight saving time |
| 1929-10-05 23:00 | -02:00 | -02 | Standard time |
| 1931-04-19 00:00 | -01:00 | -01 | Daylight saving time |
| 1931-10-03 23:00 | -02:00 | -02 | Standard time |
| 1932-04-03 00:00 | -01:00 | -01 | Daylight saving time |
| 1932-10-01 23:00 | -02:00 | -02 | Standard time |
| 1934-04-08 00:00 | -01:00 | -01 | Daylight saving time |
| 1934-10-06 23:00 | -02:00 | -02 | Standard time |
| 1935-03-31 00:00 | -01:00 | -01 | Daylight saving time |
| 1935-10-05 23:00 | -02:00 | -02 | Standard time |
| 1936-04-19 00:00 | -01:00 | -01 | Daylight saving time |
| 1936-10-03 23:00 | -02:00 | -02 | Standard time |
| 1937-04-04 00:00 | -01:00 | -01 | Daylight saving time |
| 1937-10-02 23:00 | -02:00 | -02 | Standard time |
| 1938-03-27 00:00 | -01:00 | -01 | Daylight saving time |
| 1938-10-01 23:00 | -02:00 | -02 | Standard time |
| 1939-04-16 00:00 | -01:00 | -01 | Daylight saving time |
| 1939-11-18 23:00 | -02:00 | -02 | Standard time |
| 1940-02-25 00:00 | -01:00 | -01 | Daylight saving time |
| 1940-10-07 23:00 | -02:00 | -02 | Standard time |
| 1941-04-06 00:00 | -01:00 | -01 | Daylight saving time |
| 1941-10-05 23:00 | -02:00 | -02 | Standard time |
| 1942-03-15 00:00 | -01:00 | -01 | Daylight saving time |
| 1942-04-26 00:00 | +00:00 | +00 | Daylight saving time |
| 1942-08-15 23:00 | -01:00 | -01 | Daylight saving time |
| 1942-10-24 23:00 | -02:00 | -02 | Standard time |
| 1943-03-14 00:00 | -01:00 | -01 | Daylight saving time |
| 1943-04-18 00:00 | +00:00 | +00 | Daylight saving time |
| 1943-08-28 23:00 | -01:00 | -01 | Daylight saving time |
| 1943-10-30 23:00 | -02:00 | -02 | Standard time |
| 1944-03-12 00:00 | -01:00 | -01 | Daylight saving time |
| 1944-04-23 00:00 | +00:00 | +00 | Daylight saving time |
| 1944-08-26 23:00 | -01:00 | -01 | Daylight saving time |
| 1944-10-28 23:00 | -02:00 | -02 | Standard time |
| 1945-03-11 00:00 | -01:00 | -01 | Daylight saving time |
| 1945-04-22 00:00 | +00:00 | +00 | Daylight saving time |
| 1945-08-25 23:00 | -01:00 | -01 | Daylight saving time |
| 1945-10-27 23:00 | -02:00 | -02 | Standard time |
| 1946-04-07 00:00 | -01:00 | -01 | Daylight saving time |
| 1946-10-05 23:00 | -02:00 | -02 | Standard time |
| 1947-04-06 03:00 | -01:00 | -01 | Daylight saving time |
| 1947-10-05 02:00 | -02:00 | -02 | Standard time |
| 1948-04-04 03:00 | -01:00 | -01 | Daylight saving time |
| 1948-10-03 02:00 | -02:00 | -02 | Standard time |
| 1949-04-03 03:00 | -01:00 | -01 | Daylight saving time |
| 1949-10-02 02:00 | -02:00 | -02 | Standard time |
| 1950-04-02 03:00 | -01:00 | -01 | Daylight saving time |
| 1950-10-01 02:00 | -02:00 | -02 | Standard time |
| 1951-04-01 03:00 | -01:00 | -01 | Daylight saving time |
| 1951-10-07 02:00 | -02:00 | -02 | Standard time |
| 1952-04-06 03:00 | -01:00 | -01 | Daylight saving time |
| 1952-10-05 02:00 | -02:00 | -02 | Standard time |
| 1953-04-05 03:00 | -01:00 | -01 | Daylight saving time |
| 1953-10-04 02:00 | -02:00 | -02 | Standard time |
| 1954-04-04 03:00 | -01:00 | -01 | Daylight saving time |
| 1954-10-03 02:00 | -02:00 | -02 | Standard time |
| 1955-04-03 03:00 | -01:00 | -01 | Daylight saving time |
| 1955-10-02 02:00 | -02:00 | -02 | Standard time |
| 1956-04-01 03:00 | -01:00 | -01 | Daylight saving time |
| 1956-10-07 02:00 | -02:00 | -02 | Standard time |
| 1957-04-07 03:00 | -01:00 | -01 | Daylight saving time |
| 1957-10-06 02:00 | -02:00 | -02 | Standard time |
| 1958-04-06 03:00 | -01:00 | -01 | Daylight saving time |
| 1958-10-05 02:00 | -02:00 | -02 | Standard time |
| 1959-04-05 03:00 | -01:00 | -01 | Daylight saving time |
| 1959-10-04 02:00 | -02:00 | -02 | Standard time |
| 1960-04-03 03:00 | -01:00 | -01 | Daylight saving time |
| 1960-10-02 02:00 | -02:00 | -02 | Standard time |
| 1961-04-02 03:00 | -01:00 | -01 | Daylight saving time |
| 1961-10-01 02:00 | -02:00 | -02 | Standard time |
| 1962-04-01 03:00 | -01:00 | -01 | Daylight saving time |
| 1962-10-07 02:00 | -02:00 | -02 | Standard time |
| 1963-04-07 03:00 | -01:00 | -01 | Daylight saving time |
| 1963-10-06 02:00 | -02:00 | -02 | Standard time |
| 1964-04-05 03:00 | -01:00 | -01 | Daylight saving time |
| 1964-10-04 02:00 | -02:00 | -02 | Standard time |
| 1965-04-04 03:00 | -01:00 | -01 | Daylight saving time |
| 1965-10-03 02:00 | -02:00 | -02 | Standard time |
| 1966-04-03 03:00 | -01:00 | -01 | Daylight saving time |
| 1966-10-02 03:00 | -01:00 | -01 | Standard time |
| 1982-03-28 01:00 | +00:00 | +00 | Daylight saving time |
| 1982-09-26 00:00 | -01:00 | -01 | Standard time |
| 1983-03-27 01:00 | +00:00 | +00 | Daylight saving time |
| 1983-09-25 00:00 | -01:00 | -01 | Standard time |
| 1984-03-25 01:00 | +00:00 | +00 | Daylight saving time |
| 1984-09-30 00:00 | -01:00 | -01 | Standard time |
| 1985-03-31 01:00 | +00:00 | +00 | Daylight saving time |
| 1985-09-29 00:00 | -01:00 | -01 | Standard time |
| 1986-03-30 01:00 | +00:00 | +00 | Daylight saving time |
| 1986-09-28 00:00 | -01:00 | -01 | Standard time |
| 1987-03-29 01:00 | +00:00 | +00 | Daylight saving time |
| 1987-09-27 00:00 | -01:00 | -01 | Standard time |
| 1988-03-27 01:00 | +00:00 | +00 | Daylight saving time |
| 1988-09-25 00:00 | -01:00 | -01 | Standard time |
| 1989-03-26 01:00 | +00:00 | +00 | Daylight saving time |
| 1989-09-24 00:00 | -01:00 | -01 | Standard time |
| 1990-03-25 01:00 | +00:00 | +00 | Daylight saving time |
| 1990-09-30 00:00 | -01:00 | -01 | Standard time |
| 1991-03-31 01:00 | +00:00 | +00 | Daylight saving time |
| 1991-09-29 00:00 | -01:00 | -01 | Standard time |
| 1992-03-29 01:00 | +00:00 | +00 | Daylight saving time |
| 1992-09-27 00:00 | -01:00 | -01 | Standard time |
| 1992-12-27 02:00 | +00:00 | WET | Standard time |
| 1993-03-28 02:00 | +01:00 | WEST | Daylight saving time |
| 1993-06-17 01:00 | +00:00 | +00 | Daylight saving time |
| 1993-09-26 00:00 | -01:00 | -01 | Standard time |
| 1994-03-27 01:00 | +00:00 | +00 | Daylight saving time |
| 1994-09-25 00:00 | -01:00 | -01 | Standard time |
| 1995-03-26 01:00 | +00:00 | +00 | Daylight saving time |
| 1995-09-24 00:00 | -01:00 | -01 | Standard time |
| 1996-03-31 01:00 | +00:00 | +00 | Daylight saving time |
| 1996-10-27 00:00 | -01:00 | -01 | Standard time |
| 1997-03-30 01:00 | +00:00 | +00 | Daylight saving time |
| 1997-10-26 00:00 | -01:00 | -01 | Standard time |
| 1998-03-29 01:00 | +00:00 | +00 | Daylight saving time |
| 1998-10-25 00:00 | -01:00 | -01 | Standard time |
| 1999-03-28 01:00 | +00:00 | +00 | Daylight saving time |
| 1999-10-31 00:00 | -01:00 | -01 | Standard time |
| 2000-03-26 01:00 | +00:00 | +00 | Daylight saving time |
| 2000-10-29 00:00 | -01:00 | -01 | Standard time |
| 2001-03-25 01:00 | +00:00 | +00 | Daylight saving time |
| 2001-10-28 00:00 | -01:00 | -01 | Standard time |
| 2002-03-31 01:00 | +00:00 | +00 | Daylight saving time |
| 2002-10-27 00:00 | -01:00 | -01 | Standard time |
| 2003-03-30 01:00 | +00:00 | +00 | Daylight saving time |
| 2003-10-26 00:00 | -01:00 | -01 | Standard time |
| 2004-03-28 01:00 | +00:00 | +00 | Daylight saving time |
| 2004-10-31 00:00 | -01:00 | -01 | Standard time |
| 2005-03-27 01:00 | +00:00 | +00 | Daylight saving time |
| 2005-10-30 00:00 | -01:00 | -01 | Standard time |
| 2006-03-26 01:00 | +00:00 | +00 | Daylight saving time |
| 2006-10-29 00:00 | -01:00 | -01 | Standard time |
| 2007-03-25 01:00 | +00:00 | +00 | Daylight saving time |
| 2007-10-28 00:00 | -01:00 | -01 | Standard time |
| 2008-03-30 01:00 | +00:00 | +00 | Daylight saving time |
| 2008-10-26 00:00 | -01:00 | -01 | Standard time |
| 2009-03-29 01:00 | +00:00 | +00 | Daylight saving time |
| 2009-10-25 00:00 | -01:00 | -01 | Standard time |
| 2010-03-28 01:00 | +00:00 | +00 | Daylight saving time |
| 2010-10-31 00:00 | -01:00 | -01 | Standard time |
| 2011-03-27 01:00 | +00:00 | +00 | Daylight saving time |
| 2011-10-30 00:00 | -01:00 | -01 | Standard time |
| 2012-03-25 01:00 | +00:00 | +00 | Daylight saving time |
| 2012-10-28 00:00 | -01:00 | -01 | Standard time |
| 2013-03-31 01:00 | +00:00 | +00 | Daylight saving time |
| 2013-10-27 00:00 | -01:00 | -01 | Standard time |
| 2014-03-30 01:00 | +00:00 | +00 | Daylight saving time |
| 2014-10-26 00:00 | -01:00 | -01 | Standard time |
| 2015-03-29 01:00 | +00:00 | +00 | Daylight saving time |
| 2015-10-25 00:00 | -01:00 | -01 | Standard time |
| 2016-03-27 01:00 | +00:00 | +00 | Daylight saving time |
| 2016-10-30 00:00 | -01:00 | -01 | Standard time |
| 2017-03-26 01:00 | +00:00 | +00 | Daylight saving time |
| 2017-10-29 00:00 | -01:00 | -01 | Standard time |
| 2018-03-25 01:00 | +00:00 | +00 | Daylight saving time |
| 2018-10-28 00:00 | -01:00 | -01 | Standard time |
| 2019-03-31 01:00 | +00:00 | +00 | Daylight saving time |
| 2019-10-27 00:00 | -01:00 | -01 | Standard time |
| 2020-03-29 01:00 | +00:00 | +00 | Daylight saving time |
| 2020-10-25 00:00 | -01:00 | -01 | Standard time |
| 2021-03-28 01:00 | +00:00 | +00 | Daylight saving time |
| 2021-10-31 00:00 | -01:00 | -01 | Standard time |
| 2022-03-27 01:00 | +00:00 | +00 | Daylight saving time |
| 2022-10-30 00:00 | -01:00 | -01 | Standard time |
| 2023-03-26 01:00 | +00:00 | +00 | Daylight saving time |
| 2023-10-29 00:00 | -01:00 | -01 | Standard time |
| 2024-03-31 01:00 | +00:00 | +00 | Daylight saving time |
| 2024-10-27 00:00 | -01:00 | -01 | Standard time |
| 2025-03-30 01:00 | +00:00 | +00 | Daylight saving time |
| 2025-10-26 00:00 | -01:00 | -01 | Standard time |
| 2026-03-29 01:00 | +00:00 | +00 | Daylight saving time |
| 2026-10-25 00:00 | -01:00 | -01 | Standard time |
| 2027-03-28 01:00 | +00:00 | +00 | Daylight saving time |
| 2027-10-31 00:00 | -01:00 | -01 | Standard time |