This is the standard time zone only on a few small offshore Atlantic islands. The only such island with a permanent population is Fernando de Noronha, with 3,061 inhabitants, 0.0015% of Brazil's population. The other islands either are totally uninhabited or have small seasonally rotating Brazilian Navy garrisons or teams of scientists.
This time zone is used in the states of Mato Grosso, Mato Grosso do Sul, Rondônia, Roraima, and most of Amazonas. Although this time zone covers about 34% of the land area of Brazil, slightly less than 6% of the country's population live there. Until 2008, the areas of the state of Pará west of the Xingu River and north of the Amazon River were also part of this time zone; then they joined the rest of the state in observing Brasília time. Although other changes to Brazilian time zones enacted at that time have since been reverted, western and northern Pará still remain in UTC−03:00.
Brasília time −2 (UTC−05:00)
This time zone was reinstated in 2013, after having been abolished for over five years. It is used in the far-western tip of the country, which includes the entire state of Acre and the southwestern portion of the state of Amazonas. These areas cover only about 6% of the Brazilian territory and have only about 0.6% of the country's population. On 24 June 2008, these areas advanced their clocks by an hour, so that they became part of the UTC−04:00 time zone. However, in a non-binding referendum held on 31 October 2010, a slight majority of Acre voters voted in favour of returning the state to UTC−05:00. On 30 October 2013, Brazilian PresidentDilma Rousseffenacted Law 12876, establishing that the time zone switch would occur on Sunday, 10 November 2013. Since then, the state of Acre and 13 municipalities in the southwestern part of the state of Amazonas are again 5 hours behind UTC.
Unofficial observance
Unofficially, 32 municipalities in eastern Mato Grosso, located in the Araguaia valley, observe UTC−03:00, Brasília time. This practice started in Barra do Garças in 1998. Banks and government services still observe the legal time in these locations.
Brazil observed daylight saving time in the years of 1931–1933, 1949–1953, 1963–1968 and 1985–2019. Initially it applied to the whole country, but from 1988 it applied only to part of the country, usually the southern regions, where DST is more useful due to a larger seasonal variation in daylight duration. It typically lasted from October or November to February or March. The most recent DST rule specified advancing the time by one hour during the period from 00:00 on the first Sunday in November to 00:00 on the third Sunday in February, applicable only to the South, Southeast and Central-West regions, which comprise about 64% of the Brazilian population. During DST, Brasília time moved from UTC−03:00 to UTC−02:00; the other states that did not follow DST observed a change of the offset to Brasília time. Brazil abolished DST in 2019.
