Yucatán, which corresponds to TZDB’s America/Merida, is considering
switching from -06 (CST) all year to -05 (EST) all year.[1] This would
be akin to observing permanent daylight saving time. (Yucatán last
observed DST in 2022, after which Mexico abolished DST except in regions
near the US.) There does not seem to be any rush to decide whether to
make the change.
If Yucatán does switch presumably Campeche will not, so we would
therefore need to split America/Merida into two zones, and as Mérida is
in Yucatán we would need a new name for Campeche. The largest city in
the Mexican state of Campeche is its capital San Francisco de Campeche,
commonly called just “Campeche” like the state, so presumably
America/Campeche would be the name of the new TZDB zone.
One possible date and time for Yucatán’s hypothetical switch would be
March 8, 2026 at 02:00, which is when US CST is planned to switch to
CDT. Any such transition is purely speculative at this point, though, so
I am not now proposing a patch to TZDB.
[1]: David Domínguez Massa. Posturas desde el Congreso de Yucatán sobre
homologar el horario con Quintana Roo. Diario de Yucatán. 2025-07-05.
https://www.yucatan.com.mx/merida/2025/07/05/posturas-desde-el-congreso-de-yucatan-sobre-homologar-el-horario-con-quintana-roo.html
