Time zone · Oceania
TST
Tonga Standard Time
Tonga Standard Time is a single-zone region that runs a steady UTC+13:00 year-round, making Tongatapu one of the world’s permanent 'first-to-midnight' places. No daylight-saving changes means teams here enjoy a predictable rhythm that naturally sits ahead of most global calendars.
Friday, October 16, 2026
Current offset
UTC+13:00
Standard · +13
Daylight saving
Not observed
Year-round standard time
IANA zones
1
None observe daylight saving
DST offset
—
No summer variant
About TST
A fixed, year-round offset.
Tonga Standard Time is a single-zone region that runs a steady UTC+13:00 year-round, making Tongatapu one of the world’s permanent 'first-to-midnight' places. No daylight-saving changes means teams here enjoy a predictable rhythm that naturally sits ahead of most global calendars.
IANA zones · the technical identifiers
The zone that resolve to TST.
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 TST
Local time, city by city.
1 city
Where TST is used
One country.
Same offset · UTC+13:00
Other zones at UTC+13:00 right now.
These named zones share TST's offset today. When daylight saving rules differ, they drift apart for part of the year.
Convert
TST to the world's clocks.
Frequently asked questions
Common questions about TST, daylight saving, and how to handle it in software. Can't find what you need? Email [email protected].
- Is Tonga Standard Time affected by daylight saving?
- No — Tonga Standard Time never observes daylight saving, so the UTC+13:00 offset stays constant every day of the year.
- Why does Tonga mostly use a single timezone?
- All of Tonga's islands use the same time, UTC+13:00.
- What’s distinctive about Tonga’s clock?
- UTC+13:00 places Tongatapu among the earliest countries to enter a new calendar day, often ticking over to midnight well ahead of Europe and many parts of the Americas.
- Has Tonga ever flirted with daylight saving?
- Yes. Tonga used daylight saving time (UTC+14:00) in the summers of 1999–2000, 2000–2001 and 2001–2002, and again in 2016–2017. It has not used it since January 15, 2017.
- How does UTC+13:00 affect business hours?
- Tonga's morning overlaps with the previous afternoon on the US East Coast (Tonga is 17 or 18 hours ahead of New York, depending on US daylight saving time) and with the same working day in New Zealand and eastern Australia.
- Are there quirks in how Tonga records dates?
- Tonga lies west of the International Date Line, so it shows the same clock time as nearby Niue (UTC−11:00) but is a full calendar day ahead.
- What event cemented the current offset?
- Tonga has used UTC+13:00 as its standard time since January 1, 1961. Its most recent daylight saving period ended on January 15, 2017.
- Will that offset ever change?
- No official transitions are scheduled—Tonga Standard Time looks set to remain UTC+13:00 indefinitely, adding stability for long-term scheduling.
Source: IANA tzdb2026e · 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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