The time zones actually in use in Europe differ significantly from their "pure" theoretical variants as used for example under the nautical time system. Theoretically the world is divided into 24 time zones of 15 degrees. However, due to geographical and cultural factors it is not practical to divide the world so evenly and actual time zones may differ significantly from their theoretical borders. In Europe's case, the widespread use of the Central European Time Zone causes a major distortion in some areas from the theoretical time or the solar time. CET is theoretically centred around 15°E. However, Spain lying almost entirely in the Western hemisphere, and France with some regions to the west should theoretically use UTC, as they did before the Second World War. The general result is a solar noon which is much later than clock noon. This results in later sunrises and sunsets than should theoretically happen. The Benelux countries should also theoretically use GMT.
Russia and Belarus have observed "permanent summer time" since 2011. Iceland can be considered to be on "de facto" permanent summer time because it uses UTC time all year, despite being located more than 15° west of the prime meridian. It should therefore be located in UTC-1, but chooses to remain closer to continental European time, resulting in legal times significantly in advance of local solar time.
The meridians of 0, 15°E, and 30°E mark the theoretical centres of the European time zones. However, the actual time zones extend far beyond the theoretical borders of ±7.5°
This map shows the difference between legal time and local mean time in Europe during the winter. Most of Western Europe and European Russia is significantly ahead of local solar time.
Legal time vs local mean time
1 h ± 30 m behind
0 h ± 30 m
1 h ± 30 m ahead
2 h ± 30 m ahead
This map shows the difference between legal time and local mean time in Europe during the summer. Most of Western Europe and European Russia is significantly ahead of local solar time.