In our system we have list of olson timezones, which get from http://download.geonames.org/export/dump/timeZones.txt and in this data we have correct offset only for 1 January and 1 July of the year for each timezone. That means, if some of timezone offset changes by daylight saving time in, for example 2 January, i will have not correct offset for this timezone until 1 July, when i get new data.. How or where i can get actual offset for every day for olson timezone id(America/Los_Angeles, Australia/Melbourne and others from this list)..
