Time zone · Oceania
CHST
Chamorro Standard Time
Chamorro Standard Time (CHST) keeps Guam and the Northern Mariana Islands locked to a steady UTC+10:00 year-round—no daylight saving shifts to worry about, making it refreshingly simple to coordinate across the western Pacific. Whether you're calling Saipan, Hagåtña, or a partner in Tokyo, the clock never springs forward or falls back, so your meetings stay predictable.
Saturday, June 6, 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 locked to a steady UTC+10:00 year-round—no daylight saving shifts to worry about, making it refreshingly simple to coordinate across the western Pacific. Whether you're calling Saipan, Hagåtña, or a partner in Tokyo, the clock never springs forward or falls back, so your meetings stay predictable.
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 sit just south of the tropics, daylight hours stay fairly constant year-round, so there’s little benefit to shifting clocks. The U.S. Uniform Time Act of 1966 also lets far-flung territories opt out, and both islands chose to keep one standard time.
- How does CHST compare to neighboring time zones like PGT or JST?
- ChST is one hour behind Japan Standard Time (UTC+11:00) and one hour ahead of Papua New Guinea Time (UTC+09:00), placing Guam and Saipan right in the middle of the western-Pacific workday—ideal for split-the-difference conference calls.
- Are there two different ‘Chamorro Time Zones’—Chamorro Standard Time and Chamorro Daylight Time?
- Historically, ‘Chamorro Daylight Time (ChDT, UTC+11:00) was used briefly during U.S. wartime operations, but today only Chamorro Standard Time is in effect; there’s no separate daylight-saving zone.
- What’s the farthest-east time zone in the U.S. Commonwealth?
- Chamorro Standard Time (UTC+10:00) edges out Atlantic Standard Time (UTC−04:00) in clock time—making Guam’s ChST the latest hourly offset under the U.S. flag, even if it’s ‘tomorrow’ there when it’s still ‘today’ in D.C. }, {
- Will CHST ever switch to daylight saving?
- There are no current plans; both Pacific/Guam and Pacific/Saipan keep UTC+10:00 indefinitely, so you can lock in that offset.
- Is ‘Chamorro’ different from ‘ChST’ in documents?
- They refer to the same UTC+10:00 zone—‘Chamorro Standard Time’ is just spelled out, ‘ChST’ is the abbreviation.
- How do you pronounce ‘Chamorro’?
- It’s “shuh-MOH-ro” (IPA: /ʃəˈmɒroʊ/), named after the indigenous Chamorro people of the Mariana Islands.
Free · Developer API
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