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In Guam, there is only one time zone in use: Chamorro Standard Time, ChST (UTC+10). Time in Guam does not change because it does not observe Daylight Saving Time.
For comparing the current time in Guam and United Kingdom or any other country combination, visit time comparison. For an introduction to UTC and world time, read UTC by country. Time changes in Guam are shown below by city, state or region.
| Regions | Standard Time | Daylight Saving Time | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Time zone | 2025 | 2026 | 2027 | Time zone | 2025 | 2026 | 2027 | |||
| Chamorro Standard Time ChST (UTC+10) | UTC+10 all year long | No Daylight Saving Time | |||||||
The information in this page comes from data published in the Time Zone Database managed by the Internet Assigned Numbers Authority (IANA).
| Year | Time zone Abbreviation | UTC Offset | Time zone Name | Daylight Saving Time | Begins (local time) |
|---|---|---|---|---|---|
| 2000 | ChST | UTC+10 | Chamorro Standard Time | no | Saturday, December 23 2000, 12:00 AM |
| 1977 | GST | UTC+10 | no | Sunday, August 28 1977, 02:00 AM | |
| 1977 | GDT | UTC+11 | yes | Sunday, April 24 1977, 02:00 AM | |
| 1976 | GST | UTC+10 | no | Sunday, August 22 1976, 02:01 AM | |
| 1976 | GDT | UTC+11 | yes | Wednesday, May 26 1976, 02:00 AM | |
| 1974 | GST | UTC+10 | no | Sunday, February 24 1974, 02:00 AM | |
| 1973 | GDT | UTC+11 | yes | Sunday, December 16 1973, 02:00 AM | |
| 1971 | GST | UTC+10 | no | Sunday, September 5 1971, 02:00 AM | |
| 1971 | GDT | UTC+11 | yes | Sunday, April 25 1971, 02:00 AM | |
| 1970 | GST | UTC+10 | no | Sunday, September 6 1970, 02:00 AM | |
| 1970 | GDT | UTC+11 | yes | Sunday, April 26 1970, 02:00 AM | |
| 1969 | GST | UTC+10 | no | Sunday, August 31 1969, 02:00 AM | |
| 1969 | GDT | UTC+11 | yes | Sunday, June 22 1969, 02:00 AM | |
| 1969 | GST | UTC+10 | no | Saturday, January 25 1969, 12:01 AM | |
| 1967 | GDT | UTC+11 | yes | Friday, September 1 1967, 02:00 AM | |
| 1961 | GST | UTC+10 | no | Sunday, January 29 1961, 02:00 AM | |
| 1959 | GDT | UTC+11 | yes | Saturday, June 27 1959, 02:00 AM | |
| 1944 | GST | UTC+10 | no | Monday, July 31 1944, 12:00 AM | |
| 1941 | +09 | UTC+09 | no | Tuesday, December 9 1941, 12:00 AM | |
| 1901 | GST | UTC+10 | no | Tuesday, January 1 1901, 12:00 AM | |
| 1845 | LMT | UTC+09:39 | no | Wednesday, January 1 1845, 12:00 AM |