It appears the wrong date for DST start in Cuba in 2004 is in the database. It does not follow the same rules as the years before. The correct date should be Sunday 2004-03-28 00:00 ("Mar lastSun" rather than "Apr Sun>=1"). Richard Andersen (TT) (which I believe is also on this list) pointed out the difference between http://www.timeanddate.com/worldclock/timezone.html?n=99&syear=2000 and the IANA rules for Cuba, which led me to investigate. It appears I fixed this back when this was announced that year but unfortunately never reported it here. We've recorded an old granma.cu article, now long gone: http://www.granma.cu/espanol/2004/marzo/sab27/reloj.html But fortunately still available through the Wayback Machine: https://web.archive.org/web/20040402060750/http://www.granma.cu/espanol/2004... Loosely translated to: "On Saturday, March 27 at midnight [end of day] clocks are moved ahead one hour, to begin this traditional schedule." Best regards, Steffen Thorsen - timeanddate.com