Sierra Time Zone — S
Military letter S (Sierra) maps to the UTC-6 offset from Coordinated Universal Time. Covers the U.S. Central Time zone, Mexico, and Central America.
Sierra (S) — UTC-6
Thursday, 22 October 2026 GMT-6
About Sierra
UTC offset
UTC-6
Letter S = Sierra in the NATO phonetic alphabet.
Where S is used
Covers the U.S. Central Time zone, Mexico, and Central America.
Places on UTC-6 (S time) in 2026
33 zones in the tz database are at UTC-6 for at least part of 2026. Zones listed under January or July only are on this offset for part of the year, because they change their clocks for daylight saving time. Civil abbreviations at this offset: MDT, CST.
All year (14 zones)
Belize, Canada, Costa Rica, Ecuador, El Salvador, Guatemala, Honduras, Mexico, Nicaragua
America/Bahia Banderas · America/Belize · America/Chihuahua · America/Costa Rica · America/El Salvador · America/Guatemala · America/Managua · America/Merida · America/Mexico City · America/Monterrey · America/Regina · America/Swift Current · America/Tegucigalpa · Pacific/Galapagos
In January only (12 zones)
Canada, Mexico, United States
America/Chicago · America/Indiana/Knox · America/Indiana/Tell City · America/Matamoros · America/Menominee · America/North Dakota/Beulah · America/North Dakota/Center · America/North Dakota/New Salem · America/Ojinaga · America/Rankin Inlet · America/Resolute · America/Winnipeg
In July only (7 zones)
Canada, Chile, Mexico, United States
America/Boise · America/Cambridge Bay · America/Ciudad Juarez · America/Denver · America/Edmonton · America/Inuvik · Pacific/Easter
Converting S time
In a military date-time group the zone letter follows the time: 151430S JAN 26 means 14:30 Sierra time on 15 January 2026, which is 152030Z JAN 26 in Zulu (UTC).