Web service - current time zone for a city? [closed]

Is there a web service of some sort (or any other way) to pull a current time zone settings for a (US) city. For the parts of the country that don't follow the Daylight Saving Time and basically jump timezones when everyone else is switching summer/winter time... I don't fancy creating own database of the places that don't follow DST. Is there a way to pull this data on demand?

I need this for the database server (not for client workstations) - there entities stored in the database that have City, State as properties. I need know current timezone for these entities at any moment of time.

Solution 1:

We encountered same issue and, alongside the great suggestions above, Google appears to have two complementary APIs, one for Time Zone from geocode (latitude/longitude) data and the geocode API.

For example, to get the time zone and offset for San Francisco:

1) Convert the city to a geocoded location:

http://maps.googleapis.com/maps/api/geocode/json?address=San%20Francisco,+CA&sensor=false

The geocoded location is in the JSON return data:

"location": {
    "lat":  37.77492950,
    "lng": -122.41941550
}

2) Convert the geocoded location to a local timezone and offset, if any:

https://maps.googleapis.com/maps/api/timezone/json?location=37.77492950,-122.41941550&timestamp=1331161200&sensor=false

Which returns the current time zone information:

{
          "status": "OK",
       "dstOffset":  0.0,
       "rawOffset": -28800.0,              
      "timeZoneId": "America/Los_Angeles",
    "timeZoneName": "Pacific Standard Time"
}

Time zones for a region can change for a variety of reasons. So it is a good idea to find an authoritative server-based solution and not cache. For more information see Wikipedia's Time Zone article.

Solution 2:

earthtools.org provides a free web service to get the time zone from a city here:

http://www.earthtools.org/webservices.htm#timezone

You just pass in the long/lat values like this: (This is for New York)

http://www.earthtools.org/timezone-1.1/40.71417/-74.00639

EDIT:

It seems like earthtools has been shut down. A good alternative (That did not exist in 2008 when this question was answered) is the Google Time Zone API. To use it you must first activate the Time Zone API on your account. It is free if you stay below these limits:

2500 requests per 24 hour period.
5 requests per second.

The documentation is available on Google Developers.

Solution 3:

Geonames.org has a wonderful set of worldly data that's available via webservice or download:

http://www.geonames.org/export/ws-overview.html

In particular

http://www.geonames.org/export/web-services.html#timezone

Solution 4:

Earthtool's timezone info is not up to date ... for an instance, the Sri Lankan current offset is +5.5 from GMT but EarthTools shows as +6 which was the old offset before 2005.

I suggest GeoNames.org.