Null Pointer Exception while updating Screen with temparature value

private String url="https://api.forecast.io/forecast/"+apiKey+"/"+latitude+","+longitude;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    if(isNetworkAvailable()){
        OkHttpClient okHttpClient = new OkHttpClient();
        Request request = new Request.Builder().url(url).build();
        Call call=okHttpClient.newCall(request);
        call.enqueue(new Callback() {
            @Override
            public void onFailure(Request request, IOException e) {



            }
  @Override
            public void onResponse(Response response) throws IOException {
                try{
                    if(response.isSuccessful()){
                        String jsonData=response.body().string();
                        Log.v(TAG, jsonData);
                        Log.d(TAG, url);
                        mCurrentWheather=getCurrentDetails(jsonData);
                        runOnUiThread(new Runnable() {
                            @Override
                            public void run() {
                                updateUIScreen();
                            }
                        });

                    }else{
                        alertUserOnFailure();
                    }
                }catch(IOException e){
                    Log.e(TAG,"Caught Exception : "+e);
                }catch(JSONException e){
                    Log.e(TAG,"Caught Exception : "+e);
                }
           }
        });
    }else{
        alertUserOnNetworkFailure();
        Toast.makeText(this,"No Netwrok!",Toast.LENGTH_LONG).show();
    }}
   private CurrentWheather getCurrentDetails(String jsonData) throws JSONException{

    CurrentWheather currentWheather = new CurrentWheather();

    JSONObject forecast=new JSONObject(jsonData);
    String timezone=forecast.getString("timezone");
    currentWheather.setTimeZone(timezone);
    Log.i(TAG, timezone);
    JSONObject currently =forecast.getJSONObject("currently");
    currentWheather.setHumidity(currently.getDouble("humidity"));
    currentWheather.setIcon(currently.getString("icon"));
    currentWheather.setPreciptationChance(currently.getDouble("precipProbability"));
    currentWheather.setTemparature(currently.getDouble("temperature"));
    currentWheather.setSummary(currently.getString("summary"));
    currentWheather.setTime(currently.getLong("time"));
     Log.d(TAG,currentWheather.getFormattedTime());
      return currentWheather;
}

private void updateUIScreen() {
    /*mTemparatureValue.setText(mCurrentWheather.getTemparature()+"");
    mHumidityValue.setText(mCurrentWheather.getHumidity()+"");*/
    Log.i(TAG,mCurrentWheather.getTemparature()+"");
    mTemparatureValue.setText(mCurrentWheather.getTemparature()+"");


}}
private boolean isNetworkAvailable() {

    boolean networkStatus=false;
    ConnectivityManager manager= (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo info = manager.getActiveNetworkInfo();
    assert info != null;
    if(info!=null && info.isAvailable() && info.isConnected()){
        networkStatus=true;
    }

    return networkStatus;
}