Sunday, September 13, 2015

How to get a time zone from a location using latitude and longitude coordinates?


70down votefavorite
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There are too many questions on StackOverflow about resolving a time zone from a location. This community wiki is an attempt at consolidating all of the valid responses.
Please update my answer, or add your own as you see fit.
The Question
Given the latitude and longitude of a location, how does one know what time zone is in effect in that location?
In most cases, we are looking for an IANA/Olson time zone id, although some services may return just a UTC offset, or some other time zone identifier. Please read the timezone tag info for details.
  
shareimprove this question
   
One thing I've noticed is the lack of any UTC timestamp requirement when determining the time zone. For instance, a long/lat in London is not enough to determine weather the time zone is GMT or BST (British Summer Time / daylight savings). So surely to determine the correct time zone you need lat, long and a UTC timestamp. –  Michael Waterfall Aug 17 '14 at 22:41
1 
@MichaelWaterfall - To determine whether you are in GMT (UTC+0000) or BST (UTC+0100) - yes, you are absolutely correct. But those are time zone offsets, not time zone identifiers. Both are covered by the same"Europe/London" time zone identifier of the IANA time zone database. –  Matt Johnson Aug 17 '14 at 23:34
   
Ah okay, and the daylight savings offset will be added (if required) once rendering a time with a given time zone identifier? –  Michael Waterfall Aug 20 '14 at 13:25
   
@Michael - that depends on the specific implementation, but usually, yes. –  Matt Johnson Aug 20 '14 at 14:33

9 Answers

up vote82down voteaccepted
Time Zone Location Web Services
Raw Time Zone Geolocation Data
  • tz_world - the original shapefile data from Eric Muller
  • whereonearth-timezone - GeoJSON version with WOEDB data merged in
  • CityTimeZones - crowdsourced CSV file with common cities and their Windows Time Zone ids.
Time Zone Geolocation Implementations
  • What Time is it here? - Nice blog article describing how to use tz_world data in MongoDB with PHP
  • latlong - Implements the tz_world data in a Go package. Read this post also.
  • GeoTimeZone - Implements the tz_world data in a .Net portable class library
  • TimeZoneMapper - Implements the tz_world data in a Java library.
  • tzwhere - Implements the tz_world data in a Javascript library for NodeJS applications
  • pytzwhere - Implements the tz_world data in a Python library
  • Raven.TimeZones - Implements the tz_world data in RavenDB
Libraries that call one of the web services
  • timezone - Ruby gem that calls GeoNames
  • AskGeo has its own libraries for calling from Java or .Net
  • GeoNames has client libraries for just about everything
Other Ideas
Please update this list if you know of any others
Also, note that the nearest-city approach may not yield the "correct" result, just an approximation.
Conversion To Windows Zones
Most of the methods listed will return an IANA time zone id. If you need to convert to a Windows time zone, see this post.
Don't use zone.tab
The tz database includes a file called zone.tab. This file is primarily used to present a list of time zones for a user to pick from. It includes the latitude and longitude coordinates for the point of reference for each time zone. This allows a map to be created highlighting these points. For example, see the interactive map shown on the moment-timezone home page.
While it may be tempting to use this data to resolve the time zone from a latitude and longitude coordinates, consider that these are points - not boundaries. The best one could do would be to determine the closest point, which in many cases will not be the correct point.
Consider the following example:
                            Time Zone Example Art
The two squares represent different time zones, where the black dot in each square is the reference location, such as what can be found in zone.tab. The blue dot represents the location we are attempting to find a time zone for. Clearly, this location is within the orange zone on the left, but if we just look at closest distance to the reference point, it will resolve to the greenish zone on the right.
shareimprove this answer
   
GeoNames is actually perfect for what I need. Thanks! –  Luke Apr 19 '13 at 8:59
   
@Matt However, as I understand, at the moment there is no offline database which would provide timezone info and offset from UTC based on the location coordinates? –  Martin Nov 4 '13 at 23:57
   
@Martin - Raven.TimeZones can be run completely offline. And if you don't like .NET or RavenDB, you could implement the same idea in any database that supports spatial queries. If I ever get time to learn them, I'm going to do Postgres and/or SQLite versions as well. –  Matt Johnson Nov 5 '13 at 0:00 
   
@MattJohnson how can i use geonames client libraries –  Erum Feb 18 at 6:12
up vote5down vote
How about this solution for node.js https://github.com/mattbornski/tzwhere
And its Python counterpart: https://github.com/pegler/pytzwhere
shareimprove this answer
1 
I added these to the community wiki answer above. Thanks! –  Matt Johnson Jul 12 '14 at 21:26
up vote3down vote
We at Teleport just started opening up our API's and one of the usecases is also exposing TZ information for coordinates.
For example one could request all our available TZ information for coordinates in following manner:
curl -s https://api.teleport.org/api/locations/59.4372,24.7453/?embed=location:nearest-cities/location:nearest-city/city:timezone/tz:offsets-now | jq '._embedded."location:nearest-cities"[0]._embedded."location:nearest-city"._embedded."city:timezone"'
This would return the following
{
  "_embedded": {
    "tz:offsets-now": {
      "_links": {
        "self": {
          "href": "https://api.teleport.org/api/timezones/iana:Europe%2FTallinn/offsets/?date=2015-09-07T11%3A20%3A09Z"
        }
      },
      "base_offset_min": 120,
      "dst_offset_min": 60,
      "end_time": "2015-10-25T01:00:00Z",
      "short_name": "EEST",
      "total_offset_min": 180,
      "transition_time": "2015-03-29T01:00:00Z"
    }
  },
  "_links": {
    "self": {
      "href": "https://api.teleport.org/api/timezones/iana:Europe%2FTallinn/"
    },
    "tz:offsets": {
      "href": "https://api.teleport.org/api/timezones/iana:Europe%2FTallinn/offsets/{?date}",
      "templated": true
    },
    "tz:offsets-now": {
      "href": "https://api.teleport.org/api/timezones/iana:Europe%2FTallinn/offsets/?date=2015-09-07T11%3A20%3A09Z"
    }
  },
  "iana_name": "Europe/Tallinn"
}
For the example I used ./jq for JSON parsing.
shareimprove this answer
up vote0down vote
Try this code for use Google Time Zone API from Java with current NTP Time Client and correct UTC_Datetime_from_timestamp convert:
String get_xml_server_reponse(String server_url){

    URL xml_server = null;

    String xmltext = "";

    InputStream input;


    try {
        xml_server = new URL(server_url);


        try {
            input = xml_server.openConnection().getInputStream();


            final BufferedReader reader = new BufferedReader(new InputStreamReader(input));
            final StringBuilder sBuf = new StringBuilder();

            String line = null;
            try {
                while ((line = reader.readLine()) != null) 
                {
                    sBuf.append(line);
                }
               } 
            catch (IOException e) 
              {
                    Log.e(e.getMessage(), "XML parser, stream2string 1");
              } 
            finally {
                try {
                    input.close();
                    }
                catch (IOException e) 
                {
                    Log.e(e.getMessage(), "XML parser, stream2string 2");
                }
            }

            xmltext =  sBuf.toString();

        } catch (IOException e1) {

                e1.printStackTrace();
            }


        } catch (MalformedURLException e1) {

          e1.printStackTrace();
        }

     return  xmltext;

  }     


 private String get_UTC_Datetime_from_timestamp(long timeStamp){

    try{

        Calendar cal = Calendar.getInstance();
        TimeZone tz = cal.getTimeZone();

        int tzt = tz.getOffset(System.currentTimeMillis());

        timeStamp -= tzt;

        // DateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss",Locale.getDefault());
        DateFormat sdf = new SimpleDateFormat();
        Date netDate = (new Date(timeStamp));
        return sdf.format(netDate);
    }
    catch(Exception ex){
        return "";
     }
    } 

 class NTP_UTC_Time
 {
     private static final String TAG = "SntpClient";

     private static final int RECEIVE_TIME_OFFSET = 32;
     private static final int TRANSMIT_TIME_OFFSET = 40;
     private static final int NTP_PACKET_SIZE = 48;

     private static final int NTP_PORT = 123;
     private static final int NTP_MODE_CLIENT = 3;
     private static final int NTP_VERSION = 3;

     // Number of seconds between Jan 1, 1900 and Jan 1, 1970
     // 70 years plus 17 leap days
     private static final long OFFSET_1900_TO_1970 = ((365L * 70L) + 17L) * 24L * 60L * 60L;

     private long mNtpTime;

     public boolean requestTime(String host, int timeout) {
         try {
             DatagramSocket socket = new DatagramSocket();
             socket.setSoTimeout(timeout);
             InetAddress address = InetAddress.getByName(host);
             byte[] buffer = new byte[NTP_PACKET_SIZE];
             DatagramPacket request = new DatagramPacket(buffer, buffer.length, address, NTP_PORT);

             buffer[0] = NTP_MODE_CLIENT | (NTP_VERSION << 3);

             writeTimeStamp(buffer, TRANSMIT_TIME_OFFSET);

             socket.send(request);

             // read the response
             DatagramPacket response = new DatagramPacket(buffer, buffer.length);
             socket.receive(response);          
             socket.close();

             mNtpTime = readTimeStamp(buffer, RECEIVE_TIME_OFFSET);            
         } catch (Exception e) {
           //  if (Config.LOGD) Log.d(TAG, "request time failed: " + e);
             return false;
         }

         return true;
     }


     public long getNtpTime() {
         return mNtpTime;
     }


     /**
      * Reads an unsigned 32 bit big endian number from the given offset in the buffer.
      */
     private long read32(byte[] buffer, int offset) {
         byte b0 = buffer[offset];
         byte b1 = buffer[offset+1];
         byte b2 = buffer[offset+2];
         byte b3 = buffer[offset+3];

         // convert signed bytes to unsigned values
         int i0 = ((b0 & 0x80) == 0x80 ? (b0 & 0x7F) + 0x80 : b0);
         int i1 = ((b1 & 0x80) == 0x80 ? (b1 & 0x7F) + 0x80 : b1);
         int i2 = ((b2 & 0x80) == 0x80 ? (b2 & 0x7F) + 0x80 : b2);
         int i3 = ((b3 & 0x80) == 0x80 ? (b3 & 0x7F) + 0x80 : b3);

         return ((long)i0 << 24) + ((long)i1 << 16) + ((long)i2 << 8) + (long)i3;
     }

     /**
      * Reads the NTP time stamp at the given offset in the buffer and returns 
      * it as a system time (milliseconds since January 1, 1970).
      */    
     private long readTimeStamp(byte[] buffer, int offset) {
         long seconds = read32(buffer, offset);
         long fraction = read32(buffer, offset + 4);
         return ((seconds - OFFSET_1900_TO_1970) * 1000) + ((fraction * 1000L) / 0x100000000L);        
     }

     /**
      * Writes 0 as NTP starttime stamp in the buffer. --> Then NTP returns Time OFFSET since 1900
      */    
     private void writeTimeStamp(byte[] buffer, int offset) {        
         int ofs =  offset++;

         for (int i=ofs;i<(ofs+8);i++)
           buffer[i] = (byte)(0);             
     }

 }

 String get_time_zone_time(GeoPoint gp){

        String erg = "";
        String raw_offset = "";
        String dst_offset = "";

        double Longitude = gp.getLongitudeE6()/1E6;
        double Latitude = gp.getLatitudeE6()/1E6;



        long tsLong = 0; // System.currentTimeMillis()/1000;

        NTP_UTC_Time client = new NTP_UTC_Time();

        if (client.requestTime("pool.ntp.org", 2000)) {              
          tsLong = client.getNtpTime();
        }

        if (tsLong != 0)
        {

        tsLong = tsLong  / 1000;

        // https://maps.googleapis.com/maps/api/timezone/xml?location=39.6034810,-119.6822510&timestamp=1331161200&sensor=false

        String request = "https://maps.googleapis.com/maps/api/timezone/xml?location="+Latitude+","+ Longitude+ "&timestamp="+tsLong +"&sensor=false";

        String xmltext = get_xml_server_reponse(request);

        if(xmltext.compareTo("")!= 0)
        {

         int startpos = xmltext.indexOf("<TimeZoneResponse");
         xmltext = xmltext.substring(startpos);



        XmlPullParser parser;
        try {
            parser = XmlPullParserFactory.newInstance().newPullParser();


             parser.setInput(new StringReader (xmltext));

             int eventType = parser.getEventType();  

             String tagName = "";


             while(eventType != XmlPullParser.END_DOCUMENT) {
                 switch(eventType) {

                     case XmlPullParser.START_TAG:

                           tagName = parser.getName();

                         break;


                     case XmlPullParser.TEXT :


                        if  (tagName.equalsIgnoreCase("raw_offset"))
                          if(raw_offset.compareTo("")== 0)                               
                            raw_offset = parser.getText();  

                        if  (tagName.equalsIgnoreCase("dst_offset"))
                          if(dst_offset.compareTo("")== 0)
                            dst_offset = parser.getText();  


                        break;   

                 }

                 try {
                        eventType = parser.next();
                    } catch (IOException e) {

                        e.printStackTrace();
                    }

                }

                } catch (XmlPullParserException e) {

                    e.printStackTrace();
                    erg += e.toString();
                }

        }      

        int ro = 0;
        if(raw_offset.compareTo("")!= 0)
        { 
            float rof = str_to_float(raw_offset);
            ro = (int)rof;
        }

        int dof = 0;
        if(dst_offset.compareTo("")!= 0)
        { 
            float doff = str_to_float(dst_offset);
            dof = (int)doff;
        }

        tsLong = (tsLong + ro + dof) * 1000;



        erg = get_UTC_Datetime_from_timestamp(tsLong);
        }


  return erg;

}
And use it with:
GeoPoint gp = new GeoPoint(39.6034810,-119.6822510);
String Current_TimeZone_Time = get_time_zone_time(gp);
shareimprove this answer
   
This seems like a lot of code for a simple task. You've got a full NTP client in there, which might be a good idea - but is not necessarily required. Can you slim it down a bit please? –  Matt Johnson Nov 3 '13 at 5:38
   
Yeah! This is why I don't use Java. Can you have more boilerplate please? –  Jaseem Jun 30 at 8:05
up vote0down vote
Ok here is the short Version without correct NTP Time:
String get_xml_server_reponse(String server_url){

URL xml_server = null;

String xmltext = "";

InputStream input;


try {
    xml_server = new URL(server_url);


    try {
        input = xml_server.openConnection().getInputStream();


        final BufferedReader reader = new BufferedReader(new InputStreamReader(input));
        final StringBuilder sBuf = new StringBuilder();

        String line = null;
        try {
            while ((line = reader.readLine()) != null) 
            {
                sBuf.append(line);
            }
           } 
        catch (IOException e) 
          {
                Log.e(e.getMessage(), "XML parser, stream2string 1");
          } 
        finally {
            try {
                input.close();
                }
            catch (IOException e) 
            {
                Log.e(e.getMessage(), "XML parser, stream2string 2");
            }
        }

        xmltext =  sBuf.toString();

    } catch (IOException e1) {

            e1.printStackTrace();
        }


    } catch (MalformedURLException e1) {

      e1.printStackTrace();
    }

 return  xmltext;

} 


long get_time_zone_time_l(GeoPoint gp){


        String raw_offset = "";
        String dst_offset = "";

        double Longitude = gp.getLongitudeE6()/1E6;
        double Latitude = gp.getLatitudeE6()/1E6;

        long tsLong = System.currentTimeMillis()/1000;


        if (tsLong != 0)
        {

        // https://maps.googleapis.com/maps/api/timezone/xml?location=39.6034810,-119.6822510&timestamp=1331161200&sensor=false

        String request = "https://maps.googleapis.com/maps/api/timezone/xml?location="+Latitude+","+ Longitude+ "&timestamp="+tsLong +"&sensor=false";

        String xmltext = get_xml_server_reponse(request);

        if(xmltext.compareTo("")!= 0)
        {

         int startpos = xmltext.indexOf("<TimeZoneResponse");
         xmltext = xmltext.substring(startpos);



        XmlPullParser parser;
        try {
            parser = XmlPullParserFactory.newInstance().newPullParser();


             parser.setInput(new StringReader (xmltext));

             int eventType = parser.getEventType();  

             String tagName = "";


             while(eventType != XmlPullParser.END_DOCUMENT) {
                 switch(eventType) {

                     case XmlPullParser.START_TAG:

                           tagName = parser.getName();

                         break;


                     case XmlPullParser.TEXT :


                        if  (tagName.equalsIgnoreCase("raw_offset"))
                          if(raw_offset.compareTo("")== 0)                               
                            raw_offset = parser.getText();  

                        if  (tagName.equalsIgnoreCase("dst_offset"))
                          if(dst_offset.compareTo("")== 0)
                            dst_offset = parser.getText();  


                        break;   

                 }

                 try {
                        eventType = parser.next();
                    } catch (IOException e) {

                        e.printStackTrace();
                    }

                }

                } catch (XmlPullParserException e) {

                    e.printStackTrace();
                    erg += e.toString();
                }

        }      

        int ro = 0;
        if(raw_offset.compareTo("")!= 0)
        { 
            float rof = str_to_float(raw_offset);
            ro = (int)rof;
        }

        int dof = 0;
        if(dst_offset.compareTo("")!= 0)
        { 
            float doff = str_to_float(dst_offset);
            dof = (int)doff;
        }

        tsLong = (tsLong + ro + dof) * 1000;


        }


  return tsLong;

}
And use it with:
GeoPoint gp = new GeoPoint(39.6034810,-119.6822510);
long Current_TimeZone_Time_l = get_time_zone_time_l(gp);
shareimprove this answer
up vote0down vote
If you want to use geonames.org then use this code. (But geonames.org is very slow sometimes)
String get_time_zone_time_geonames(GeoPoint gp){


        String erg = "";

        double Longitude = gp.getLongitudeE6()/1E6;
        double Latitude = gp.getLatitudeE6()/1E6;



        String request = "http://ws.geonames.org/timezone?lat="+Latitude+"&lng="+ Longitude+ "&style=full";

        URL time_zone_time = null;

        InputStream input;
       // final StringBuilder sBuf = new StringBuilder();


        try {
            time_zone_time = new URL(request);


        try {
            input = time_zone_time.openConnection().getInputStream();


        final BufferedReader reader = new BufferedReader(new InputStreamReader(input));
            final StringBuilder sBuf = new StringBuilder();

            String line = null;
            try {
                while ((line = reader.readLine()) != null) {
                    sBuf.append(line);
                }
            } catch (IOException e) {
                    Log.e(e.getMessage(), "XML parser, stream2string 1");
            } finally {
                try {
                    input.close();
                } catch (IOException e) {
                    Log.e(e.getMessage(), "XML parser, stream2string 2");
                }
            }




             String xmltext = sBuf.toString();


             int startpos = xmltext.indexOf("<geonames");
             xmltext = xmltext.substring(startpos);



            XmlPullParser parser;
            try {
                parser = XmlPullParserFactory.newInstance().newPullParser();


            parser.setInput(new StringReader (xmltext));

            int eventType = parser.getEventType();  

            String tagName = "";

            while(eventType != XmlPullParser.END_DOCUMENT) {
                switch(eventType) {

                    case XmlPullParser.START_TAG:

                          tagName = parser.getName();

                        break;


                    case XmlPullParser.TEXT :


                        if  (tagName.equalsIgnoreCase("time"))
                          erg = parser.getText();  


                    break;   

                }

                try {
                    eventType = parser.next();
                } catch (IOException e) {

                    e.printStackTrace();
                }

            }

            } catch (XmlPullParserException e) {

                e.printStackTrace();
                erg += e.toString();
            }



            } catch (IOException e1) {

                e1.printStackTrace();
            }


            } catch (MalformedURLException e1) {

                e1.printStackTrace();
            }





        return erg;

 }
And use it with:
GeoPoint gp = new GeoPoint(39.6034810,-119.6822510);
String Current_TimeZone_Time = get_time_zone_time_geonames(gp);
shareimprove this answer
up vote0down vote
by using latitude and longitude get time zone of current location below code worked for me
String data = null;         
LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
Location ll = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
double lat = 0,lng = 0;
if(ll!=null){
    lat=ll.getLatitude();
    lng=ll.getLongitude();
}
System.out.println(" Last known location of device  == "+lat+"    "+lng);

InputStream iStream = null; 
HttpURLConnection urlConnection = null;
try{
    timezoneurl = timezoneurl+"location=22.7260783,75.8781553&timestamp=1331161200";   //&key=AIzaSyDZMS5Za6yG_66gAK8PL_KH1ZSS9NbWC";                   
    // timezoneurl = timezoneurl+"location="+lat+","+lng+"&timestamp=1331161200";//&key=AIzaSyDZMS5Za6yG_66gAK8PL_KH1ZSS9NbWCbg";

    URL url = new URL(timezoneurl);                
    // Creating an http connection to communicate with url 
    urlConnection = (HttpURLConnection) url.openConnection(); 

    // Connecting to url 
    urlConnection.connect();                

    // Reading data from url 
    iStream = urlConnection.getInputStream();

    BufferedReader br = new BufferedReader(new InputStreamReader(iStream));

    StringBuffer sb  = new StringBuffer();
    String line = "";
    while( ( line = br.readLine())  != null){
        sb.append(line);
    }
    data = sb.toString();
    br.close();

}catch(Exception e){
    Log.d("Exception while downloading url", e.toString());
}finally{
    try {
        iStream.close();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    urlConnection.disconnect();
}

try {
    if(data!=null){
        JSONObject jobj=new JSONObject(data);
        timezoneId = jobj.getString("timeZoneId");

        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
        format.setTimeZone(TimeZone.getTimeZone(timezoneId));

        Calendar cl = Calendar.getInstance(TimeZone.getTimeZone(timezoneId));
        System.out.println("time zone id in android ==  "+timezoneId);

        System.out.println("time zone of  device in android == "+TimeZone.getTimeZone(timezoneId));
        System.out.println("time fo device in android "+cl.getTime());
    }
} catch (Exception e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}
shareimprove this answer
4 
Which service are you calling? And did you really want to share your keys with us?? –  Matt Johnson Nov 6 '14 at 17:23
up vote-1down vote
And here is a good implementation using JSON data: https://github.com/agap/llttz
public TimeZone nearestTimeZone(Location node) {
    double bestDistance = Double.MAX_VALUE;
    Location bestGuess = timeZones.get(0);

    for (Location current : timeZones.subList(1, timeZones.size())) {
        double newDistance = distanceInKilometers(node, current);

        if (newDistance < bestDistance) {
            bestDistance = newDistance;
            bestGuess = current;
        }
    }

    return java.util.TimeZone.getTimeZone(bestGuess.getZone());
}

  protected double distanceInKilometers(final double latFrom, final double lonFrom, final double latTo, final double lonTo) {
        final double meridianLength = 111.1;
        return meridianLength * centralAngle(latFrom, lonFrom, latTo, lonTo);
    }

    protected double centralAngle(final Location from, final Location to) {
        return centralAngle(from.getLatitude(), from.getLongitude(), to.getLatitude(), to.getLongitude());
    }

    protected double centralAngle(final double latFrom, final double lonFrom, final double latTo, final double lonTo) {
        final double latFromRad = toRadians(latFrom),
                lonFromRad = toRadians(lonFrom),
                latToRad   = toRadians(latTo),
                lonToRad   = toRadians(lonTo);

        final double centralAngle = toDegrees(acos(sin(latFromRad) * sin(latToRad) + cos(latFromRad) * cos(latToRad) * cos(lonToRad - lonFromRad)));

        return centralAngle <= 180.0 ? centralAngle : (360.0 - centralAngle);
    }

    protected double distanceInKilometers(final Location from, final Location to) {
        return distanceInKilometers(from.getLatitude(), from.getLongitude(), to.getLatitude(), to.getLongitude());
    }
}
shareimprove this answer
   
Can you also add some content from the links? –  Robert Aug 19 at 11:04
up vote-4down vote
If you prefer to avoid a web service, you can retrieve that information from the browser like this:
var d = new Date();
var usertime = d.toLocaleString();

//some browsers / OSs provide the timezone name in their local string
var tzsregex = /\b(ACDT|ACST|ACT|ADT|AEDT|AEST|AFT|AKDT|AKST|AMST|AMT|ART|AST|AWDT|AWST|AZOST|AZT|BDT|BIOT|BIT|BOT|BRT|BST|BTT|CAT|CCT|CDT|CEDT|CEST|CET|CHADT|CHAST|CIST|CKT|CLST|CLT|COST|COT|CST|CT|CVT|CXT|CHST|DFT|EAST|EAT|ECT|EDT|EEDT|EEST|EET|EST|FJT|FKST|FKT|GALT|GET|GFT|GILT|GIT|GMT|GST|GYT|HADT|HAEC|HAST|HKT|HMT|HST|ICT|IDT|IRKT|IRST|IST|JST|KRAT|KST|LHST|LINT|MART|MAGT|MDT|MET|MEST|MIT|MSD|MSK|MST|MUT|MYT|NDT|NFT|NPT|NST|NT|NZDT|NZST|OMST|PDT|PETT|PHOT|PKT|PST|RET|SAMT|SAST|SBT|SCT|SGT|SLT|SST|TAHT|THA|UYST|UYT|VET|VLAT|WAT|WEDT|WEST|WET|WST|YAKT|YEKT)\b/gi;

//in other browsers the timezone needs to be estimated based on the offset
var timezonenames = {"UTC+0":"GMT","UTC+1":"CET","UTC+2":"EET","UTC+3":"EEDT","UTC+3.5":"IRST","UTC+4":"MSD","UTC+4.5":"AFT","UTC+5":"PKT","UTC+5.5":"IST","UTC+6":"BST","UTC+6.5":"MST","UTC+7":"THA","UTC+8":"AWST","UTC+9":"AWDT","UTC+9.5":"ACST","UTC+10":"AEST","UTC+10.5":"ACDT","UTC+11":"AEDT","UTC+11.5":"NFT","UTC+12":"NZST","UTC-1":"AZOST","UTC-2":"GST","UTC-3":"BRT","UTC-3.5":"NST","UTC-4":"CLT","UTC-4.5":"VET","UTC-5":"EST","UTC-6":"CST","UTC-7":"MST","UTC-8":"PST","UTC-9":"AKST","UTC-9.5":"MIT","UTC-10":"HST","UTC-11":"SST","UTC-12":"BIT"};

var timezone = usertime.match(tzsregex);
if (timezone) {
    timezone = timezone[timezone.length-1];
} else {
    var offset = -1*d.getTimezoneOffset()/60;
    offset = "UTC" + (offset >= 0 ? "+" + offset : offset);
    timezone = timezonenames[offset];
}

//there are 3 variables can use to see the timezone
// usertime - full date
// offset - UTC offset time
// timezone - country

console.log('Full Date: ' + usertime);
console.log('UTC Offset: ' + offset);
console.log('Country Code Timezone: ' + timezone);
In my current case it is printing:
Full Date: ‎27‎/‎01‎/‎2014‎ ‎16‎:‎53‎:‎37 UTC Offset: UTC-3 Country Code Timezone: BRT
Hope it can be helpful.
shareimprove this answer
   
While I appreciate you put some effort into this, please realize: 1) Time zones are not fixed offsets 2) Time zone abbreviations are not standardized or unique identifiers 3) This has already been done, much more accurately, with jsTimeZoneDetect. 4) Your answer doesn't match the question. The question was how to determine a time zone from latitude and longitude coordinates. –  Matt Johnson Jan 27 '14 at 20:44

Your Answer http://stackoverflow.com/questions/16086962/how-to-get-a-time-zone-from-a-location-using-latitude-and-longitude-coordinates/16086964#16086964

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