Daylight saving time is called "horário de verão", or HV, in Brazil.

Rules currently in force

Brazil sets its daylight saving period by decree every year. Consequently, rules for Brazil spanning more than one year can only be established by induction. Since 2002, in even-numbered years, the spring date for setting clocks ahead has been advanced from October to November in order to avoid affecting elections. It was reported that voting machines couldn't be programmed to accept a time change between the two voting dates in the election cycle.

Geographical notes:

Brazil adopted standard time on 1914-01-01. The transition occurred at 00:00, according to standard time for each location. Before then, each location had observed local mean time. Law no. 2784, dated 1913-06-18, defined four time zones for Brazil.

The first zone, Pernambuco's eastern zone, consisted of Fernando de Noronha and the other Atlantic islands of Trindade, Martin Vaz, Atol das Rocas, and Penedos de Sao Pedro e Sao Paulo. Its standard time was UTC-2, with the other zones progressively earlier by one hour each.

The second zone consisted of Pernambuco's western zone (the mainland part of the state), Pará's eastern zone, and the present-day states of Alagoas, Amapa, Bahia, Ceará, Distrito Federal, Espírito Santo, Goias, Maranhão, Minas Gerais, Paraiba, Paraná, Piauí, Rio de Janeiro, Rio Grande do Norte, Rio Grande do Sul, Santa Catarina, São Paulo, Sergipe, and Tocantins.

The dividing line between Pará's eastern and western zones ran from the mouth of Rio Jari at the border with Amapa, up the Amazon to the mouth of Rio Xingu, and up the Xingu to the border with Mato Grosso. The cities of Belém, Marabá, São Félix do Xingu, and Serra Norte lay in the eastern zone. Altamira, Óbidos, Oriximiná, Prainha, and Santarém lay in the western zone.

The third zone consisted of Pará's western zone, Amazonas's eastern zone, and the present-day states of Mato Grosso, Mato Grosso do Sul, Rondonia, and Roraima. The fourth zone contained the rest of Amazonas and Acre.

The division between Amazonas's zones was the great circle passing through Tabatinga and Porto Acre, with those two cities included in the eastern zone. Tabatinga is located at 4°14'27"S, 69°56'32"W; Pôrto Acre is at 9°35'16"S 67°32'08"W, and actually lies in Acre state (as it also did in 1913). Cities in the eastern zone included Boca do Acre, Floriano Peixoto, Jutai, and Manaus; in the west were Atalaia do Norte, Benjamin Constant, Boca do Maoco, Eirunepé, Envira, and Ipixuna.

These zones remained unchanged until 2008. Then, Law 11.662  moved the clock ahead one hour in Acre, the western zone of Amazonas, and the western zone of Pará. It took effect at 2008-06-24 00:00. As a result, Brazil has only three time zones, and each state except Pernambuco lies in only one zone.

Time zone history

The following table shows the standard time for each state in Brazil, as the zones and states stand now. To find out whether a state was observing HV on a given date, find its code letter in the "Code" column. If the column is blank, that state has never observed HV since mid-1988. Go on to the following table. Before 2008, Acre was on UTC-5, and Amazonas and Pará were split between two zones; see above.

If a local time is between the "Start of HV" and "End of HV" on one of the rows of this table, and the code letter for the location is listed in the "Coverage" column (or the Coverage is "All"), then HV was in effect at that local time at that location. The "E" coverage code represents the western zone of Amazonas, abolished in 2008. "U" represents eastern Amazonas.

References

Decretos sobre o Horário de Verão no Brasil  has links to all the official decrees defining summer time in Brazil since 1931. Note that the government frequently changes its mind at the last minute.