Time zone · Americas
AST
Amazon Standard Time
Amazon Standard Time (AST) is Brazil's steadfast clock—five cities across the Amazon basin sharing a reliable UTC-04:00 that never springs forward or falls back. No daylight saving means easier logistics and simpler scheduling, whether you're coordinating flights out of Porto Velho or syncing trade calls from Manaus during the seasonal pulse of the rainforest.
Saturday, May 30, 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) is Brazil's steadfast clock—five cities across the Amazon basin sharing a reliable UTC-04:00 that never springs forward or falls back. No daylight saving means easier logistics and simpler scheduling, whether you're coordinating flights out of Porto Velho or syncing trade calls from Manaus during the seasonal pulse of the rainforest.
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.
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.
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].
- Which cities in Brazil follow Amazon Standard Time?
- AST covers Manaus, Boa Vista, Porto Velho, Campo Grande, and Cuiabá—key hubs flanking or embedded within the Amazon biome.
- Does any part of Amazon Standard Time observe daylight saving time?
- No. Amazon Standard Time is fixed at UTC-04:00 year-round, removing the need to adjust schedules or re-plan recurring meetings.
- Why did these regions stop changing clocks for daylight saving?
- A 2019 presidential decree abolished daylight-saving adjustments in Brazil's North and part of the Center-West regions, reflecting the minimal daylight variation near the equator.
- How does a fixed UTC-04:00 offset affect cross-border business with neighboring countries?
- Neighboring regions like northern Venezuela (UTC-04) often share the same offset, simplifying coordination, while Andean countries shift between UTC-4 and UTC-5, creating a moving time relationship.
- Does the Amazon rainforest experience large seasonal changes in daylight hours?
- Because all AST zones are close to the equator, daylight length stays roughly 12 hours throughout the year, making clock changes for daylight saving largely unnecessary.
- Is Amazon Standard Time the same as Brasília Time?
- No. Brasília Standard Time (BRT, UTC-03) is one hour ahead of AST; the Amazon zone remains one full hour behind Brazil's political capital.
Free · Developer API
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