Hello again, You are right: it corresponds to the DST time transition in France (I think you have guessed it was France from my "Frenglish" style - sorry about it).
To get around this problem, I now use : as.numeric(format(strptime("2010-03-28 02:00:00", format="%Y-%m-%d %H:%M:%S"), format="%H")) Thanks again for your help. Ptit Bleu. -- View this message in context: http://r.789695.n4.nabble.com/Problem-with-as-POSIXlt-hour-tp2255758p2255997.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.