Thanks, Stefanie. I conducted a lot of our recent research regarding timekeeping in Portugal and her possessions in 2024. Most of that work is summarized in this commit: https://github.com/eggert/tz/commit/43450cbf86f8219750e328ed598dd2f8782b9f3f
That work did turn up the legal text you attached to your message, Decreto Regional 5/82/M, which was published 1982-04-03. As you highlighted, the law starts by referring back to the fact that Decreto-Lei 47233 of 1966-10-01 had established year-round UTC+0 on Madeira (in fact, it abolished DST across Portugal's mainland and adjacent islands). Although mainland Portugal later resumed semiannual clock changes in September 1976, both the Azores and Madeira did not resume them until early 1982. While the Azores did so in March, it seems there was a delay in publishing this law for Madeira — Article 3 only brought it into force the day after it was published in early April. As you alluded to, this all seems to match what I wrote about in 2024. Your message, however, prompted me to review my notes, and I noticed that I had missed that legislation from 1947 and 1948 actually did make reference to the Azores and Madeira, so we no longer need to characterize the islands' observance of DST from 1947 through 1966 as an assumption. Proposed patch to commentary attached. This means, where we actually would want better proof that the islands were (or weren't) congruent with Lisbon is from anytime *before* 1947. That may not show up in legal texts so much as in things like newspaper records. -- Tim Parenti On Tue, 26 May 2026 at 13:57, Stefanie Schlosser via tz <[email protected]> wrote: > Dear IANA team, > > For personal reasons, I've been trying to find out about DST on Madeira > Island, Portugal during the past century. Long story short. I've researched > a lot and along the way I've been told that even IANA is actually missing > some records for when Madeira Island was congruent in its time changes with > mainland Portugal (Lisbon) and when it did its own thing. > I've eventually found the original law text for Madeira Island from 1982 > and am hereby submitting it to you. You don't have any mistake in your > tzdb, but seemingly part of it is based on the assumption that Madeira did > not apply DST under certain years, and you didn't have prove of it. Here > comes the prove. :) > > With best regards, > Stefanie Schlosser >
0001-Update-commentary-on-Portuguese-islands-1947-to-1966.patch
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