It won't help in a lot of cases, it's really hard to come up with a heuristic that approximates the reality (see http://www.worldtimezone.com/ for what timezones actually look like) and does not get it wrong for many important cities. It needs to be looked up in a database, if it's going to be done this way.
It won't help in a lot of cases, it's really hard to come up with a heuristic that approximates the reality (see http:// www.worldtimezo ne.com/ for what timezones actually look like) and does not get it wrong for many important cities. It needs to be looked up in a database, if it's going to be done this way.