updateDisplay() giving FATAL EXCEPTION: Main ?

    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    ButterKnife.bind(this);


    String apiKey = "*********************************";
    double latitude = 37.8267;
    double longitude = -122.423;
    String forecastURL = "https://api.forecast.io/forecast/" + apiKey + "/" +
                            latitude + "," + longitude;

    if (isNetworkAvailable())
    {
        OkHttpClient client = new OkHttpClient();
        Request request = new Request.Builder()
                .url(forecastURL)
                .build();
        Call call = client.newCall(request);

        call.enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {

            }

            @Override
            public void onResponse(Call call, Response response) throws IOException
            {
                try
                {
                    String jsonData = response.body().string();
                    if (response.isSuccessful()) {
                        mCurrentWeather = getCurrentDetails(jsonData);
                        runOnUiThread(new Runnable() {
                            @Override
                            public void run() {
                                updateDisplay();
                            }
                        });

                    }
                    else
                    {
                        alertUserError();
                    }
                }
                catch (IOException | JSONException e) {
                    Log.e(TAG, "Exception caught: ", e);
                }
            }
        });
    }
    else
    {
        Toast.makeText(this, R.string.networkUnavailable, Toast.LENGTH_LONG).show();
    }
}

            private void updateDisplay() {

            mTemperatureLabel.setText(String.format("%d", mCurrentWeather.getTemperature()));
            mTimeLabel.setText(String.format("At %d it will be", mCurrentWeather.getTime()));
            mHumidityValue.setText(String.format("%s", mCurrentWeather.getHumidity()));
            mPrecipValue.setText(String.format("%d", mCurrentWeather.getPrecipChance()) + "%");
            mSummaryLabel.setText(mCurrentWeather.getSummary());

            Drawable drawable = ContextCompat.getDrawable(this, mCurrentWeather.getIconID());
            mIconImageView.setImageDrawable(drawable);
}