Time in Portugal
Portugal has two time zones and observes daylight saving time. Continental Portugal and Madeira use UTC+00:00, while the Azores use UTC–01:00. Daylight saving time (locally known as Hora de Verão) is observed nationwide from the last Sunday in March to the last Sunday in October, so that every year, continental Portugal and Madeira temporarily use UTC+01:00, and the Azores temporarily use UTC+00:00.
In the early 19th century, Portugal adopted mean solar time. Navy (located in Lisbon) and Coimbra Astronomical Observatories calculated solar time to be used as legal time in their longitude regions. In 1861, the Astronomical Observatory of Lisbon was founded and, in 1878, it was tasked with the exclusive competence of calculate its mean solar time and to transmit it to rest of the country’s public services. Thus, in practice, Portuguese standard time was defined as the mean solar time at Lisbon Observatory longitude, which was later calculated as being GMT–00:36:44.
In 1911, it was agreed that standard time in Portugal should be defined in accordance with the 1884 prime meridian system. By the Decree of 26 May 1911, a reform was approved regarding standard time in Portugal and in its overseas Empire: although almost all continental Portugal is located west of the 7.5°W meridian (i.e. in the theoretical zone of GMT–01:00 time zone), for mainland Portugal it was adopted GMT+00:00 as its time zone. By the same law, GMT–02:00 time zone was adopted for the Azores and Cape Verde, GMT–01:00 for Madeira and Portuguese Guinea, GMT for São Tomé and Príncipe and São João Baptista de Ajudá, GMT+01:00 for Angola, GMT+02:00 for Mozambique, GMT+05:00 for Portuguese India and GMT+08:00 for Macau and Portuguese Timor. These time zones were adopted on 1 January 1912.
Daylight saving time (Hora de Verão, in Portuguese) was observed for the first time in 1916, during World War I, and it consisted in to advance clocks by 1 hour.  In that year, DST was observed from 17 June to 1 November but in following years until 1921, it was observed from 1 June to 14 October.
DST continued to be observed every year in 1920s and 1930s, although some small interruptions had occurred (1922–1923, 1925, 1930 and 1933), as well as DST’s start and end dates which were often changed.
In the years 1942–1945, during World War II, Portugal, not only advanced clocks by 1 hour during DST, as also advanced them by another 1 hour during some months of those years, coming to have clocks 2 hours ahead of GMT, during that “double DST”. Situation returned to normality after 1945, with the end of World War II, and normal DST continued to be observed. In 1948, it was approved that DST should be observed from the first Sunday in April to the first Sunday in October.
From 1966 on, DST started to be observed year-round, so that, in practice, Portugal changed its time zone from WET (GMT+00:00) to CET (GMT+01:00). However, due to the later sunrises and sunsets, many complaints had been accumulated: in winter mornings, people went to their works with a completely dark sky and at 9:00, sun was still rising. When school classes started, sun was still rising, which eventually had repercussions in students’ school performance, as well as in their safety during the morning trips from home to school. Furthermore, in the 1970s, the idea of reintroduce DST as an energy saving measure gained strength in Europe as well as in Portugal. However, in the country, if already there were so many complaints with the usage of GMT+01:00 year round, it became clear for policymakers that if DST was introduced, it could never be observed as CEST (GMT+02:00), and the only solution was to re-adopt WET as standard time. So, in 1976, Portugal adopted WET (GMT+00:00) as its standard time. DST started to be observed every year as WEST (GMT+01:00) usually from early April to later September. From 1981 on, DST started to be observed from the last Sunday in March to the last Sunday in September.
In 1992, during Cavaco Silva government, by Decree-Law 124/92, mainland Portugal officially changed its time zone from WET (UTC+00:00) to CET (UTC+01:00). CEST (UTC+02:00) began to be observed as DST, from the last Sunday in March to the last Sunday in September. The measure, approved without the consultation of Lisbon Observatory, had the intention of to promote energy savings, to make that “Portugal follow, in work schedules, the countries with which it maintains more frequent contacts” (DL 124/92) and so, to promote economic growth. However, the measure quickly proved to be a failure in to achieve its objectives and become unpopular: like in the 1967–1976 period, on winter mornings, sun was still rising at 9:00, and people went to their works with a completely dark sky. Obviously, children also went to school with a completely dark sky, and when school classes started, sun was still rising, which had repercussions on their standards of learning, school performance and sleeping habits. It was even common that children fall asleep on the early morning classes. In summer evenings, the usage of CET and CEST revealed to have a disturbing effect on people’s sleeping habits, particularly on children's ones as sun was still setting at 22:00 or 22:30, therefore sky was only completely dark near midnight, and sometimes, only at 1:00 of the following day. A company hired by European Commission conducted a study which concluded that, in fact, no energy savings happened, because in the early morning, due to the dark sky, workers turn on lights in their offices, and forgot to turn them off, leaving them switched on during the rest of the morning, what incremented energy consumption. It also emerged concerns about the effect that the coincidence of rush hours with the hottest hours of the day could have in air pollution. Furthermore, it was observed an increase in the number of assaults on children in the morning, and insurance companies reported a rise in the number of accidents.  Due to all of these concerns and complaints, it became clear that situation could not continue much longer without a new analysis. In December 1995, the government (now led by António Guterres) commissioned a report to Lisbon Observatory on the issue of Portuguese standard time. In February 1996, the Observatory report was released and it concluded that due to the geographical position of Portugal, the country should adopt WET (UTC+00:00) as its time zone, position that the policymakers decided to follow.
In 1996, new legislation was approved. By Decree-Law 17/96, mainland Portugal adopted WET (UTC+00:00) as its time zone. DST would continue to be observed as WEST (UTC+01:00) from the last Sunday in March to the last Sunday in October, thus adopting EU rules regarding DST. In the same year, Azores and Madeira regional parliaments also approved regional laws who adopted EU rules to their time zones, thus making that DST started to be observed from the last Sunday in March to last Sunday in October in the whole country.
Daylight saving time
Portugal observes EU DST rules.
Date and time notation
IANA time zone database
- History of time in Portugal (Astronomical Observatory of Lisbon) (in Portuguese). Retrieved 12 May 2013.
- Time in continental Portugal since 1911 (Astronomical Observatory of Lisbon) (in Portuguese). Retrieved 14 May 2013.
- Decree of 26 May 1911 (in Portuguese). Retrieved 12 May 2013.
- Decree 2433, 9 June 1916 (in Portuguese). Retrieved 12 May 2013.
- Decree-Law 37048, 7 September 1948 (in Portuguese). Retrieved 19 May 2013.
- Decree-Law 47233, 1 October 1966 (in Portuguese). Retrieved 12 May 2013.
- Decree-Law 309/76, 27 April 1976 (in Portuguese). Retrieved 12 May 2013.
- Marques, Manuel (February 2002), A Hora Legal em Portugal, O Observatório (in Portuguese), vol. 8, nr. 2, Lisbon, Portugal, Astronomical Observatory of Lisbon. Retrieved 12 May 2013.
- Decree-Law 44-B/86, 7 March 1986 (in Portuguese). Retrieved 19 May 2013.
- Decree-Law 124/92, 2 July 1992 (in Portuguese). Retrieved 12 May 2013.
- Assembly of the Republic – session of 8 February 1996 Diário da Assembleia da República (I Series) (in Portuguese), 7th Parliament of the 3rd Portuguese Republic (1995–1999), 1st Legislative Session (1995–1996), p. 1056, 9 February 1996. Retrieved 15 May 2013.
- Raposo, Pedro (March 2006), Com as horas trocadas, O Observatório (in Portuguese), vol. 12, nr. 3, p. 5, Lisbon, Portugal, Astronomical Observatory of Lisbon. Retrieved 26 May 2013.
- Fuso horário ainda divide opiniões (in Portuguese), Oporto, Portugal, Jornal de Notícias (24 October 2009). Retrieved 14 May 2013.
- Segurar as rédeas do tempo tem muito que se lhe diga (in Portuguese), Lisbon, Portugal, Público (24 October 2009) (only for subscribers) (copy of the notice find in the following personal websites As Palavras dos Outros, Geopedrados). Retrieved 21 May 2013
- Decree-Law 17/96, 8 March 1996 (in Portuguese). Retrieved 12 May 2013.
- "Lighter Evenings (Experiment) Bill [HL]".. Retrieved 26 May 2013.
- Comunicado do Conselho de Ministros, 21 de Dezembro de 1995 (in Portuguese), Presidency of the Council of Ministers (21 December 1995), Arquivo da Web Portuguesa. Retrieved 21 May 2013.
- Hora de Verão: Relógios em Portugal adiantam 60 minutos dia 30 (in Portuguese), Lisbon, Portugal, Agência Lusa (12 March 1997), Arquivo da Web Portuguesa. Retrieved 21 May 2013.
- Legislation on time in Portugal (Astronomical Observatory of Lisbon) (in Portuguese). Retrieved 12 May 2013.
- Regional Legislative Decree 6/96/M (Madeira), 25 June 1996 (in Portuguese). Retrieved 26 May 2013.
- Regional Legislative Decree 16/96/A (Azores), 1 August 1996 (in Portuguese). Retrieved 26 May 2013.
- (Portuguese) Fernando Correia de Oliveira (2003). História do tempo em Portugal: elementos para uma história do tempo, da relojoaria e das mentalidades em Portugal. SOCTIP. p. 324. ISBN 978-972-98861-1-9.