Time Zones of Mexico
|Basic time zone concepts|
On 2001-02-01, a decree was published in Mexico's Diario Oficial, modifying the country's time zone rules. The rules for the year 2001, to remain in force until modified by some future decree, are as shown in the table. The times of transition are local time as measured before the transition takes place, unless otherwise specified.
Distrito Federal wanted to exempt itself from DST. The Supreme Court denied the exemption in April, 2001, and the district did observe DST. Since then, the court has issued a new ruling. If nothing else changes, Distrito Federal is free to remain on standard time next summer (2002).
|States||Standard||DST||Duration of DST|
|Baja California Norte||UTC-8||UTC-7||From the first Sunday in April at 02:00 until the last Sunday in October at 02:00|
|Baja California Sur, Chihuahua, Nayarit, Sinaloa||UTC-7||UTC-6||From the first Sunday in May at 02:00 until the last Sunday in September at 02:00|
|Aguascalientes, Campeche, Chiapas, Coahuila, Colima, Distrito Federal, Durango, Guanajuato, Guerrero, Hidalgo, Jalisco, México, Michoacán, Morelos, Nuevo León, Oaxaca, Puebla, Querétaro, Quintana Roo, San Luis Potosí, Tabasco, Tamaulipas, Tlaxcala, Veracruz, Yucatán, and Zacatecas||UTC-6||UTC-5||From the first Sunday in May at 02:00 until the last Sunday in September at 02:00|
Sources: This information was adapted from the tz database. Zone names come from that database. The names were chosen according to certain rules, but don't necessarily match any names used in the "real world".
The information from the tz database has been slightly modified in light of a report prepared by research assistants to the Mexican Chamber of Deputies. It summarizes the provisions of eighteen decrees that affected Mexican time standards from 1921 to 1999.
Example: When it was 14:18 (or 2:18 p.m.) local time on 1985-04-20 (April 20, 1985) in Ensenada, Mexico, what was the UTC?
Ensenada is in the state of Baja California Norte. From the first table, Baja California Norte is in the America/Tijuana time zone. (This is a specialized meaning of "time zone", which is more precise than common usage.) Its code letter is 'J'. In the second table, look in the column headed 'J', and in the row headed '1982-12-02 00:00' (which is the latest date not exceeding the one you're trying to convert). At the intersection of that row and column is "-8 R2". That means that, on the given date, Ensenada was in a time zone whose standard time was UTC-8, and was following Rule R2 to determine the period of daylight saving time. Looking in the third table, by Rule R2, April 20 was not in the daylight saving period, so no adjustment is needed. The offset at that time was UTC-8. Add eight hours to the given time to get UTC. The answer is 1985-04-20 22:18 UTC.
|Find the Code for the given location.|
|Baja California Norte||America/Tijuana||J|
|Baja California Sur||America/Mazatlan||H|
|San Luis Potosí||America/Mexico_City||F|
|Find the UTC Offset (hours) and Daylight Saving Rule for the given time, date, and Code.|
|Ab initio||All places observed Local Mean Time until 1922-01-01 00:00 (as measured after the transition).|
|1954-01-01 00:00||-6||-6||-6||-6||-6||-6||-6||-8||-8||-8 R1|
|1976-01-01 00:00||-6||-6||-6||-6||-6||-6||-6||-7||-7||-8 R2|
|1981-12-01 00:00||-5||-5||-6||-6||-6||-6||-6||-7||-7||-8 R2|
|1982-12-02 00:00||-5||-6||-6||-6||-6||-6||-6||-7||-7||-8 R2|
|1986-01-01 00:00||-6||-6||-6||-6||-6||-6||-6||-7||-7||-8 R3|
|1988-01-01 00:00||-6||-6||-6 R3||-6 R3||-6||-6||-6||-7||-7||-8 R3|
|1989-01-01 00:00||-6||-6||-6||-6||-6||-6||-6||-7||-7||-8 R3|
|1996-01-01 00:00||-6 R3||-6 R3||-6 R3||-6 R3||-6 R3||-6 R3||-6 R3||-7 R3||-7 R3||-8 R3|
|1997-10-26 02:00||-5 R3||-6 R3||-6 R3||-6 R3||-6 R3||-6 R3||-6 R3||-7 R3||-7 R3||-8 R3|
|1998-01-01 00:00||-5 R3||-6 R3||-6 R3||-6 R3||-6 R3||-6 R3||-6||-7 R3||-7 R3||-8 R3|
|1998-08-02 02:00||-6 R3||-6 R3||-6 R3||-6 R3||-6 R3||-6 R3||-7 R3||-7 R3||-7 R3||-8 R3|
|1999-01-01 00:00||-6 R3||-6 R3||-6 R3||-6 R3||-6 R3||-6 R3||-7 R3||-7 R3||-7||-8 R3|
|2001-01-01 00:00||-6 R4||-6 R4||-6 R4||-6 R4||-6 R4||-6 R4||-7 R4||-7 R4||-7||-8 R3|
|If there is a Daylight Saving Rule, check the time and date against this table. Add one hour to the UTC Offset if the condition is met. For example, if the UTC Offset is -7 and the Daylight Saving Rule applies, that changes the offset to -6.|
|R1||from the last Sunday in April at 02:00 until the last Sunday in September at 02:00|
|R2||from the last Sunday in April at 02:00 until the last Sunday in October at 02:00|
|R3||from the first Sunday in April at 02:00 until the last Sunday in October at 02:00|
|R4||from the first Sunday in May at 02:00 until the last Sunday in September at 02:00|
In Mexico, time zones are called husos horarios. Formally, each time zone is identified by its central meridian. For example, the zone where standard time is UTC minus seven hours is called la hora del meridiano 105° oeste de Greenwich. During the daylight saving period, this same area is said to observe la hora del meridiano 90°.... Daylight Saving Time is usually called Horario de Verano. Standard time is known as Horario de Invierno, or occasionally hora oficial or hora normal. Time zone names are rarely used in Mexico. When they are used, they're not consistent. The names in the Guía Roji, a Mexican road atlas, are simply translations of the corresponding U.S. zone names. The abbreviations in the tz database don't have any official standing, but they, too, are based on the U.S. time zones.
|Parliamentary Gazette 2000-03-29||Zona del Centro||Zona Pacífico||Zona Noroeste|
|Decree of 1923-12||Hora del Este||Hora del Centro||Hora del Oeste|
|Decree of 1930-11-15||Hora del Golfo|
H. del G.
|Hora del Centro|
H. del C.
|Hora del Oeste|
H. del O.
|Guía Roji 1995||Hora Oficial del Centro||Hora Oficial de las Montañas||Hora Oficial del Pacífico|
|tz database||CST, CDT||MST, MDT||PST, PDT|
The list of decrees says (translated), "Before time zones were implemented in Mexico, standard time (also known as Hora del Ferrocarril - Railroad Time) was the time of the meridian of Tacubaya." Tacubaya was the site of an observatory in Mexico City, now functioning only as a point of interest. Its mean solar time would have been GMT minus 06:36:48. Railroad Time was eliminated by the decree of 1932-01-21.
|Back to main statoids page||Last updated: 2001-02-20|
|Copyright © 2001, 2003, 2004 by Gwillim Law.|