Time zone · Americas
AST
Amazon Standard Time
Amazon Standard Time (AST) covers key cities deep in Brazil's Amazon region and neighboring states, all set at UTC-04:00 all year with no daylight saving time.
Wednesday, October 14, 2026
Current offset
UTC-04:00
Standard · -04
Daylight saving
Not observed
Year-round standard time
IANA zones
5
None observe daylight saving
DST offset
—
No summer variant
About AST
A fixed, year-round offset.
Amazon Standard Time (AST) covers key cities deep in Brazil's Amazon region and neighboring states, all set at UTC-04:00 all year with no daylight saving time.
IANA zones · the technical identifiers
The 5 zones that resolve to AST.
For software, always store the IANA identifier — never the abbreviation alone. The database keeps these zones distinct because their rules can, and historically did, diverge.
Cities across AST
Local time, city by city.
4 cities
Where AST is used
One country.
Same offset · UTC-04:00
Other zones at UTC-04:00 right now.
These named zones share AST's offset today. When daylight saving rules differ, they drift apart for part of the year.
Convert
AST to the world's clocks.
Frequently asked questions
Common questions about AST, daylight saving, and how to handle it in software. Can't find what you need? Email [email protected].
- Why don't these Amazon-region zones use daylight saving time?
- Since they sit close to the equator, cities like Manaus and Boa Vista don’t experience big seasonal swings in daylight, so there’s little practical benefit to shifting clocks forward or back.
- Is Amazon Standard Time the same as Atlantic Standard Time?
- They share the same UTC-04:00 offset, but Atlantic Standard Time is used in Canada’s Atlantic provinces and the Caribbean, while Amazon Standard Time is specific to parts of Brazil. Canada's Atlantic provinces move to UTC-03:00 in summer, so the two match only in winter there.
- What are the main cities in Amazon Standard Time?
- Representative cities include Manaus, Boa Vista, Porto Velho, Cuiaba, and Campo Grande, spread across several northern and central-western states of Brazil.
- Does any DST ever used in these zones?
- Yes, in the past. Cuiabá and Campo Grande observed daylight saving time every summer until Brazil abolished it in 2019. Manaus last used it in 1994, Boa Vista in 2000 and Porto Velho in 1988.
- How does AST offset affect scheduling with São Paulo or Rio?
- Amazon Standard Time is one hour behind São Paulo and Rio (UTC-03:00) all year, so noon in Manaus is 1 p.m. in São Paulo. Brazil has not observed daylight saving time since 2019.
- Which Brazilian states follow AST?
- Amazon Standard Time is used in Roraima, Rondônia, Mato Grosso, Mato Grosso do Sul and most of Amazonas; the far west of Amazonas uses Acre Time.
- Is Amazon Time the same across the entire Amazon region?
- No. Acre and the far west of Amazonas use Acre Time (UTC-05:00), and Pará and Amapá use UTC-03:00, while Manaus and the rest of Amazonas follow Amazon Standard Time.
- How does constant UTC-4 affect daily life in AST?
- With no clock changes, people in Amazon Standard Time can plan schedules consistently, making business, school, and transport timetables more predictable throughout the year.
- How does AST relate to international time zones during coordination?
- Because AST never shifts for DST, global teams can use it as a stable reference—AST is always UTC-4, simplifying calendar invites and recurring calls with these Brazilian regions.
Source: IANA tzdb2026d · Reviewed
Free · Developer API
This time zone, as JSON.
Its defining offset, DST status and member counts, from one endpoint.
Also in the API: time zones by coordinates, conversions that flag daylight saving gaps, and abbreviations decoded.
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