Mexico uses three different UTC offsets as defined in the federal Law of Time Systems:¹

• Zone 1 (Central Zone) covers most of Mexico and is equivalent to UTC-6 (the equivalent of Canadian and U.S. Central Time Zone).
• Zone 2 (Pacific Zone) covers the states of Baja California Sur, Chihuahua, Nayarit, Sinaloa, and Sonora, which use UTC-7 (the equivalent of Canadian and U.S. Mountain Time Zone).
• Zone 3 (Northwest Zone) covers the state of Baja California and uses UTC-8 (the equivalent of Canadian and U.S. Pacific Time Zone).

In addition, the law dictates that all island territories should fall within the time zone corresponding to their geographic location.

Daylight saving time

Daylight saving time (horario estacional in Spanish as referred to in the law, but horario de verano in colloquial speech) has been observed in Mexico beginning in 1996.² It does not coincide with the longer extended daylight saving period adopted for 2007 in the United States. Rather, the law dictates that daylight saving time be observed between 2 a.m. on the first Sunday in April through 2 a.m. on the last Sunday in October.³

As the Unite States now starts DST on the second Sunday in March and ends it on the first Sunday in November, Mexico's time zones are now out of synchronization with the United States' Pacific, Mountain, and Central time zones for two periods each year, during which Mexico City clocks match those in Denver instead of those in Chicago. The first is the three or four weeks between the second Sunday in March and the first Sunday in April. The second is the single week between the last Sunday in October and the first Sunday in November. The Mexican Stock Exchange changes its hours during these periods in order to maintain synchronization with the U.S. markets.

In 2001 Mexico experimented with a shorter daylight saving period from the first Sunday in May till the last Sunday in September.⁴

Daylight saving time is observed in all parts of the country except for the state of Sonora, which decided to remain on standard time beginning in 1999⁵ to coincide with the non-observation in southern Arizona, with which Sonora shares a border. The island territories do not currently observe daylight time either. During DST period, Mexico uses 4 different time zones.

In Baja California daylight saving time has been observed for several decades and until 1996 was the only Mexican state to observe DST.

References