Notes
The table shows the hours and minutes to be added or subtracted
from Greenwich Mean Time in order to determine the local time in
the city listed.
A star next to the city name indicates that Daylight Saving Time
is in force in the location concerned.
The World is divided into longitudinal segments each of which is
15 degrees wide. The time in each one is offset by one hour from
the adjacent segments. The offset is either positive or negative
with respect to Greenwich Mean Time depending on whether the segment
is to the West or East of Greenwich.
So it should be easy to calculate what time it is in another city but
in practice the time zone boundaries are diverted to avoid unnecessarily
splitting up a country.
More of a problem still is the somewhat arbitrary use of daylight saving
schemes (DST) which may or may not be used by different countries within the
same zone and which frequently start or end on different dates. Many
countries are still experimenting with these schemes so it is not certain
from one year to the next whether or not there will be daylight saving in
that country.
When is DST applied ?
DST is applied in the local spring/summer time which of course, is dfferent
for northern and southern hemispheres, hence the two columns in the table.
Australia (NSW, Vic, ACT, SA) from the last Sunday in October to the last Sunday in March
Australia (Tasmania) from the first Sunday in October to the last Sunday in March
New Zealand from the first Sunday in October to the first Sunday on/after 15 March
Russia from the last Sunday in March to the first Sunday in September
UK/Europe from the last Sunday in March to the last Sunday in October
USA/Canada from the first Sunday in April to the last Sunday in October