tzdata rule group
Port
Historical rule context · 3 represented zones
A rule group describes recurring clock changes. It is not itself a place or an IANA time-zone identifier.
- First rule
- 1916
- Last rule
- 1986
- Rule entries
- 45
- Source files
- europe
Notes from the time database
Context for this rule
These source notes are preserved from tzdata. They help explain a rule’s period, without adding claims beyond the source.
Decreto 1469 of 1915-03-30 ... had nothing to do with DST; rather it regulated the sending of time signals. But we do see linkage to Spain in the 1920s below. According to the Observatory, standard time was first advanced by Decreto 2433 of 1916-06-09 and restored by Decreto 2712 of 1916-10-28. While Whitman gives 1916-10-31 for the latter transition, Shanks & Pottenger agrees more closely with the decree, which stated that its provision "will start sixty minutes after the end of 31 October, according to the current time," i.e., 01:00 on 1 November.
Midsummer
Where it appears
Zones using Port
Only historically distinct canonical zones from this atlas are listed.
PortugalOriginal rule fields
Recorded rule entries
Structured directly from tzdata’s Rule lines.
| From | To | Type | In | On | At | Save |
|---|---|---|---|---|---|---|
| 1916 | only | - | Jun | 17 | 23:00 | 1:00 |
| 1916 | only | - | Nov | 1 | 1:00 | 0 |
| 1917 | 1921 | - | Mar | 1 | 0:00 | 1:00 |
| 1917 | 1921 | - | Oct | 14 | 24:00 | 0 |
| 1924 | only | - | Apr | 16 | 23:00s | 1:00 |
| 1924 | only | - | Oct | 4 | 23:00s | 0 |
| 1926 | only | - | Apr | 17 | 23:00s | 1:00 |
| 1926 | 1929 | - | Oct | Sat>=1 | 23:00s | 0 |
| 1927 | only | - | Apr | 9 | 23:00s | 1:00 |
| 1928 | only | - | Apr | 14 | 23:00s | 1:00 |
| 1929 | only | - | Apr | 20 | 23:00s | 1:00 |
| 1931 | only | - | Apr | 18 | 23:00s | 1:00 |
| 1931 | 1932 | - | Oct | Sat>=1 | 23:00s | 0 |
| 1932 | only | - | Apr | 2 | 23:00s | 1:00 |
| 1934 | only | - | Apr | 7 | 23:00s | 1:00 |
| 1934 | 1938 | - | Oct | Sat>=1 | 23:00s | 0 |
| 1935 | only | - | Mar | 30 | 23:00s | 1:00 |
| 1936 | only | - | Apr | 18 | 23:00s | 1:00 |
| 1937 | only | - | Apr | 3 | 23:00s | 1:00 |
| 1938 | only | - | Mar | 26 | 23:00s | 1:00 |
| 1939 | only | - | Apr | 15 | 23:00s | 1:00 |
| 1939 | only | - | Nov | 18 | 23:00s | 0 |
| 1940 | only | - | Feb | 24 | 23:00s | 1:00 |
| 1940 | only | - | Oct | 7 | 23:00s | 0 |
| 1941 | only | - | Apr | 5 | 23:00s | 1:00 |
| 1941 | only | - | Oct | 5 | 23:00s | 0 |
| 1942 | 1945 | - | Mar | Sat>=8 | 23:00s | 1:00 |
| 1942 | only | - | Apr | 25 | 22:00s | 2:00 |
| 1942 | only | - | Aug | 15 | 22:00s | 1:00 |
| 1942 | 1945 | - | Oct | Sat>=24 | 23:00s | 0 |
| 1943 | only | - | Apr | 17 | 22:00s | 2:00 |
| 1943 | 1945 | - | Aug | Sat>=25 | 22:00s | 1:00 |
| 1944 | 1945 | - | Apr | Sat>=21 | 22:00s | 2:00 |
| 1946 | only | - | Apr | Sat>=1 | 23:00s | 1:00 |
| 1946 | only | - | Oct | Sat>=1 | 23:00s | 0 |
| 1947 | 1966 | - | Apr | Sun>=1 | 2:00s | 1:00 |
| 1947 | 1965 | - | Oct | Sun>=1 | 2:00s | 0 |
| 1976 | only | - | Sep | lastSun | 1:00 | 0 |
| 1977 | only | - | Mar | lastSun | 0:00s | 1:00 |
| 1977 | only | - | Sep | lastSun | 0:00s | 0 |
| 1978 | 1980 | - | Apr | Sun>=1 | 1:00s | 1:00 |
| 1978 | only | - | Oct | 1 | 1:00s | 0 |
| 1979 | 1980 | - | Sep | lastSun | 1:00s | 0 |
| 1981 | 1986 | - | Mar | lastSun | 0:00s | 1:00 |
| 1981 | 1985 | - | Sep | lastSun | 0:00s | 0 |