Macau: time zone history, and your birth hour

The clocks in Macau have changed 71 times since 1900. Today they run on UTC+8; the last change was on 21 Oct 1979. A calculator that uses today’s offset for every birth is out by some minutes for anyone born in any of the different eras below.

Since 1925, the widest gap is the summer time from 1942: 120 minutes, enough to move nearly all of births into a different two-hour period.

Every era

From – to	Clock	Versus today · births in another hour
1 Jan 1900 – 30 Oct 1904	UTC+7:34 local mean time	−26 min about 22%
30 Oct 1904 – 22 Dec 1941	UTC+8 standard time	same
22 Dec 1941 – 1 May 1942	UTC+9 wartime, on Tokyo time	+60 min about 50%
1 May 1942 – 17 Nov 1942	UTC+10 summer time	+120 min nearly all
17 Nov 1942 – 1 May 1943	UTC+9 wartime, on Tokyo time	+60 min about 50%
1 May 1943 – 30 Sep 1943	UTC+10 summer time	+120 min nearly all
30 Sep 1943 – 30 Sep 1945	UTC+9 wartime, on Tokyo time	+60 min about 50%
30 Sep 1945 – 1 May 1946	UTC+8 standard time	same
1946–1979, 32 stretches each stretch 1 May 1946 – 30 Sep 1946 · UTC+9 20 Apr 1947 – 30 Nov 1947 · UTC+9 3 May 1948 – 31 Oct 1948 · UTC+9 3 Apr 1949 – 29 Oct 1949 · UTC+9 2 Apr 1950 – 28 Oct 1950 · UTC+9 1 Apr 1951 – 28 Oct 1951 · UTC+9 6 Apr 1952 – 1 Nov 1952 · UTC+9 5 Apr 1953 – 31 Oct 1953 · UTC+9 21 Mar 1954 – 30 Oct 1954 · UTC+9 20 Mar 1955 – 5 Nov 1955 · UTC+9 18 Mar 1956 – 4 Nov 1956 · UTC+9 24 Mar 1957 – 3 Nov 1957 · UTC+9 23 Mar 1958 – 2 Nov 1958 · UTC+9 22 Mar 1959 – 1 Nov 1959 · UTC+9 20 Mar 1960 – 6 Nov 1960 · UTC+9 19 Mar 1961 – 5 Nov 1961 · UTC+9 18 Mar 1962 – 4 Nov 1962 · UTC+9 24 Mar 1963 – 3 Nov 1963 · UTC+9 22 Mar 1964 – 1 Nov 1964 · UTC+9 18 Apr 1965 – 17 Oct 1965 · UTC+9 17 Apr 1966 – 16 Oct 1966 · UTC+9 16 Apr 1967 – 22 Oct 1967 · UTC+9 21 Apr 1968 – 20 Oct 1968 · UTC+9 20 Apr 1969 – 19 Oct 1969 · UTC+9 19 Apr 1970 – 18 Oct 1970 · UTC+9 18 Apr 1971 – 17 Oct 1971 · UTC+9 16 Apr 1972 – 22 Oct 1972 · UTC+9 22 Apr 1973 – 21 Oct 1973 · UTC+9 30 Dec 1973 – 20 Oct 1974 · UTC+9 20 Apr 1975 – 19 Oct 1975 · UTC+9 18 Apr 1976 – 17 Oct 1976 · UTC+9 13 May 1979 – 21 Oct 1979 · UTC+9	UTC+9 in summer, UTC+8 the rest of the year	up to 60 min about 50%
21 Oct 1979 – today	UTC+8 standard time	same

The second figure in each row is the births moved into another two-hour period: about m/120 of them when the clock is m minutes out. For Kuala Lumpur, 30 minutes out from 1946 to 1981, the measured share is 26.0% of 4,000 sampled births.

Born in summer time?

In each of these, the clocks ran ahead of standard time. A birth inside one happened that much earlier by the sun than the clock said; give the birthplace and this site’s calculator takes it off for you.

From 19 Apr 1970, 03:30 to 18 Oct 1970, 03:30 · 60 minutes ahead
From 18 Apr 1971, 03:30 to 17 Oct 1971, 03:30 · 60 minutes ahead
From 16 Apr 1972, 03:30 to 22 Oct 1972, 03:30 · 60 minutes ahead
From 22 Apr 1973, 03:30 to 21 Oct 1973, 03:30 · 60 minutes ahead
From 30 Dec 1973, 03:30 to 20 Oct 1974, 03:30 · 60 minutes ahead
From 20 Apr 1975, 03:30 to 19 Oct 1975, 03:30 · 60 minutes ahead
From 18 Apr 1976, 03:30 to 17 Oct 1976, 03:30 · 60 minutes ahead
From 13 May 1979, 03:30 to 21 Oct 1979, 03:30 · 60 minutes ahead

Times are on the local clock: when each began the clocks went forward, and when it ended they went back.

Sources

The IANA time zone database, its asia file: every row on this page is computed from it

Every era

Born in summer time?

Check a birth

Sources