Time Zone change for San Luis, Argentina

Norberto Nazabal nazabal at gmail.com
Mon Mar 16 19:18:47 UTC 2009

Hi Jesper,

Thanks for you answer, I want to let you know that currently we are using
the GMT-4 time zone here at San Luis, since the last Sunday 15th at 00:00.
I checked the Chile DST and I think we will use the same time zone, but I
will try to contact to somebody in the goverment to confirm that
Thanks for your notes about the consistency issues and I hope the new time
zone for San Luis can be added to your database after the confirmation of
which time zone we will use.


Norberto Nazabal.

2009/3/16 Jesper Nørgaard <jnorgard at prodigy.net.mx>

>  Norberto Nazabal wrote:
> >Basically the law says:
> >1) We will use the time zone GMT-3 from the 0 hour of the second Sunday
> of October to the 24 hours of the second Saturday of April.
> >2) We will use the time zone GMT-4 from the 0 hour of the second Sunday
> of April to the 24 hours of the second Saturday of October.
> I agree that this is an accurate translation of the document which was
> published already back in December 2008. However this definition contains
> serious problems of consistency. And not only that, if this was published so
> long back (2-3 months) why was it not followed in 2009, but rather following
> the Chile DST and Buenos Aires Argentinian DST instead with a frantic press
> conference the Thursday before the weekend when it was implemented?
> The problem of consistency is the perhaps not obvious fact that the Second
> Saturday of a month at 24:00 is *not* always the same time as the Second
> Sunday at 0:00 of a month. Thus the above definition is not always defining
> two contiguous periods (DST and non-DST) as one might think. I am sure this
> is an attempt to give an intuitive definition where one period goes to the
> 24:00 hours of one day, and is replaced with a new period starting at 0:00
> hour the next day, but it fails. The first problem will occur in 2012 where
> the Second Saturday is 14.th. of April while the Second Sunday is the 8.th.
> of April (e.g. the problem occurs when the first in the month is a Sunday).
> So literally the definition will have it that GMT-3 will be followed from
> 2011-10-09 00:00:00 to 2012-04-14 24:00:00 and GMT-4 will be followed from
> 2012-04-08 00:00:00 : During a week we have both GMT-3 and GMT-4 ??
> The most probable scenarios are that either San Luis redefines the decree
> in a consistent way, or that either Chile DST or Argentina DST is followed.
> The future will tell. Already in October 2009 the two latter are different,
> Chile starts DST 2009-10-11 00:00:00 and Buenos Aires starts DST 2009-10-18
> 00:00:00.
> Regards, Jesper Nørgaard Welen
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