Time zone · Oceania
CHST
Chamorro Standard Time
Chamorro Standard Time (ChST) keeps Guam and the Northern Mariana Islands on a consistent UTC+10:00 year-round — no daylight saving shifts to worry about. Life here runs on island time in the truest sense: sunny, steady, and reliably ten hours ahead of UTC.
Sunday, May 31, 2026
Current offset
UTC+10:00
Standard · ChST
Daylight saving
Not observed
Year-round standard time
IANA zones
2
None observe daylight saving
DST offset
—
No summer variant
About CHST
A fixed, year-round offset.
Chamorro Standard Time (ChST) keeps Guam and the Northern Mariana Islands on a consistent UTC+10:00 year-round — no daylight saving shifts to worry about. Life here runs on island time in the truest sense: sunny, steady, and reliably ten hours ahead of UTC.
IANA zones · the technical identifiers
The 2 zones that resolve to CHST.
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 currently on CHST
The same hour, city by city.
2 cities · all UTC+10:00
Where CHST is used
2 countries.
Same offset · UTC+10:00
Other zones at UTC+10:00 right now.
These named zones share CHST's offset today. When daylight saving rules differ, they drift apart for part of the year.
Frequently asked questions
Common questions about CHST, daylight saving, and how to handle it in software. Can't find what you need? Email [email protected].
- Why doesn’t Chamorro Standard Time observe daylight saving?
- Because Guam and the Northern Mariana Islands are close to the equator, day length stays fairly constant year-round, making daylight saving unnecessary for energy savings or lifestyle adjustments.
- What places use Chamorro Standard Time?
- Only two U.S. territories in the western Pacific: Guam and the Northern Mariana Islands, both of which stay on ChST permanently.
- Is Chamorro Standard Time the same as Australian Eastern Standard Time?
- They share the same UTC+10:00 offset, but Australian states may observe daylight saving, while ChST does not—so they diverge during parts of the year.
- How does business scheduling work across time zones with ChST?
- Since ChST is fixed at UTC+10:00 with no DST, scheduling stays predictable—just remember it’s often early morning in ChST when it’s business hours in the U.S. East Coast.
- What’s unique about Chamorro Standard Time’s history?
- ChST was formally adopted in 2000 when Guam aligned with the Northern Mariana Islands, replacing older local time standards to simplify regional coordination.
- Does Chamorro Standard Time ever change clocks?
- No—ChST is fixed year-round. There are no spring-forward or fall-back transitions, making it one of the simplest time zones in the Pacific.
- How does ChST relate to the International Date Line?
- Being at UTC+10:00 places ChST just west of the Date Line, so it’s among the first places on Earth to welcome a new day—often ahead of mainland Asia and Oceania.
- Can I rely on ChST for long-term planning?
- Absolutely. With no DST and minimal political or geographic complexity, ChST offers stable, predictable timekeeping ideal for travel, logistics, or remote collaboration.
Free · Developer API
Time, as JSON.
Every IANA time zone with live offsets, DST status, and the countries and cities that use them — clean, dependable JSON. Sign up free and get an API key in seconds.
countries, cities, convert, DST transitions coming next.
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