As of moments ago, the Ministry of Energy in Chile has announced the new schema for DST. 

From 2019, Chile will end DST (jump from UTC -3 to UTC -4) on the first sunday of April (2019-04-07T03:00:00Z); and will start DST (from UTC -4 to UTC -3) the first sunday of September (2019-09-08T04:00:00Z)

Also, the Ministry (Susana Jimenez) announced this decision will stick until 2021; and that Magallanes will keep its own time zone (but there will be meetings to talk about this)

Announcement in video (in spanish): https://twitter.com/MinEnergia/status/1029000399129374720

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Juan Correa Poblete
PS Labs (http://www.pslabs.cl)