Time Zone America / Montevideo

Question

If I calculated the current local time in Montevideo with the following code:

var dt = new Date().toLocaleString("en-US", {timeZone: "America/Montevideo"}) console.log(dt); 

I get:

11/29/2015, 9:46:10 AM

If I checked this time on the Internet, for example: http://www.zeitverschiebung.net/en/timezone/america--montevideo I get:

11/29/2015, 8:46:10 AM

Why is there a 1st difference?

Answer 1

The time zone rules for Uruguay have changed in the 2015f version of the IANA time zone data , which is probably what the website uses - but I suspect your browser is still using relatively old time zone data.

Relevant rules in 2015e:

 Rule Uruguay 2006 max - Oct Sun>=1 2:00 1:00 S Rule Uruguay 2007 max - Mar Sun>=8 2:00 0 - 

And the equivalent in 2015f:

 Rule Uruguay 2006 2014 - Oct Sun>=1 2:00 1:00 S Rule Uruguay 2007 2015 - Mar Sun>=8 2:00 0 - 

This basically means that since 2015, Uruguay has not taken into account summer savings.

Notes:

 # From Steffen Thorsen (2015-06-30): # ... it looks like they will not be using DST the coming summer: # http://www.elobservador.com.uy/gobierno-resolvio-que-no-habra-cambio-horario-verano-n656787 # http://www.republica.com.uy/este-ano-no-se-modificara-el-huso-horario-en-uruguay/523760/ # From Paul Eggert (2015-06-30): # Apparently restaurateurs complained that DST caused people to go to the beach # instead of out to dinner. # From Pablo Camargo (2015-07-13): # http://archivo.presidencia.gub.uy/sci/decretos/2015/06/cons_min_201.pdf # [dated 2015-06-29; repeals Decree 311/006 dated 2006-09-04] 

Answer 2

This is a really interesting situation! This is definitely a summer time problem. It so happened that the government of Uruguay decided to cancel summer savings this year, and this led to several sites becoming outdated, since every year before that, summer savings began in October.

A very similar problem occurred in Israel a few years ago when the government decided to change the announced DST date, and this raised a number of DST issues with automated systems over the course of several weeks.

This ad is about Uruguay DST: http://www.elobservador.com.uy/gobierno-resolvio-que-no-habra-cambio-horario-verano-n656787