I'm getting a run time error on my weather app.

private String mIcon;
private long mTime;
private double mTemperature;
private double mHumidity;
private double mPrecipChance;
private String mSummary;
private String mTimeZone;

public String getTimeZone() {
    return mTimeZone;
}

public void setTimeZone(String timeZone) {
    mTimeZone = timeZone;
}

public String getIcon() {
    return mIcon;
}

public int getIconId() {

    int iconId = R.drawable.clear_day;

    if (mIcon.equals("clear-day")) {
        iconId = R.drawable.clear_day;
    }
    else if (mIcon.equals("clear-night")) {
        iconId = R.drawable.clear_night;
    }
    else if (mIcon.equals("rain")) {
        iconId = R.drawable.rain;
    }
    else if (mIcon.equals("snow")) {
        iconId = R.drawable.snow;
    }
    else if (mIcon.equals("sleet")) {
        iconId = R.drawable.sleet;
    }
    else if (mIcon.equals("wind")) {
        iconId = R.drawable.wind;
    }
    else if (mIcon.equals("fog")) {
        iconId = R.drawable.fog;
    }
    else if (mIcon.equals("cloudy")) {
        iconId = R.drawable.cloudy;
    }
    else if (mIcon.equals("partly-cloudy-day")) {
        iconId = R.drawable.partly_cloudy;
    }
    else if (mIcon.equals("partly-cloudy-night")) {
        iconId = R.drawable.cloudy_night;
    }

    return iconId;
}

public void setIcon(String icon) {
    mIcon = icon;
}

public long getTime() {
    return mTime;
}

public String getFormattedTime() {
    SimpleDateFormat formatter = new SimpleDateFormat("h:mm a");
    formatter.setTimeZone(TimeZone.getTimeZone(getTimeZone()));
    Date dateTime = new Date(getTime() * 1000);
    String timeString = formatter.format(dateTime);

    return timeString;
}

public void setTime(long time) {
    mTime = time;
}

public int getTemperature() {
    return (int)Math.round(mTemperature);
}


public void setTemperature(double temperature) {
    mTemperature = temperature;
}

public double getHumidity() {
    return mHumidity;
}

public void setHumidity(double humidity) {
    mHumidity = humidity;
}

public int getPrecipChance() {
    double precipPercentage = mPrecipChance * 100;
    return (int)Math.round(mPrecipChance);
}

public void setPrecipChance(double precipChance) {
    mPrecipChance = precipChance;
}

public String getSummary() {
    return mSummary;
}

public void setSummary(String summary) {
    mSummary = summary;
}

public static final String TAG = MainActivity.class.getSimpleName();

private CurrentWeather mCurrentWeather;

@InjectView(R.id.timeLabel) TextView mTimeLabel;
@InjectView(R.id.temperatureLabel) TextView mTemperatureLabel;
@InjectView(R.id.humidityValue) TextView mHumidityValue;
@InjectView(R.id.precipValue) TextView mPrecipValue;
@InjectView(R.id.summaryLabel) TextView mSummaryLabel;
@InjectView(R.id.iconImageView) ImageView mIconImageView;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    ButterKnife.inject(this);

    String apiKey = "18e4ee183959a025876f867b12eeea41";
    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(Request request, IOException e) {

            }

            @Override
            public void onResponse(Response response) throws IOException {
                try {
                    String jsonData = response.body().string();
                    Log.v(TAG, jsonData);
                    if (response.isSuccessful()) {
                        mCurrentWeather = getCurrentDetails(jsonData);
                        runOnUiThread(new Runnable() {
                            @Override
                            public void run() {
                                updateDisplay();
                            }
                        });
                    } else {
                        alertUserAboutError();
                    }
                } catch (IOException e) {
                    Log.e(TAG, "Exception caught: ", e);
                }
                catch (JSONException e) {
                    Log.e(TAG, "Exception caught: ", e);
                }
            }
        });

    }
    else {
        Toast.makeText(this, getString(R.string.network_unavailable_message), Toast.LENGTH_LONG).show();
    }

    Log.d(TAG, "Main UI code is running");
}

private void updateDisplay() {
    mTemperatureLabel.setText(mCurrentWeather.getTemperature() + "");
    mTimeLabel.setText("At" + mCurrentWeather.getFormattedTime() + "it will be");
    mHumidityValue.setText(mCurrentWeather.getHumidity() + "");
    mPrecipValue.setText(mCurrentWeather.getPrecipChance() + "%");
    mSummaryLabel.setText(mCurrentWeather.getSummary());

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

}

private CurrentWeather getCurrentDetails(String jsonData) throws JSONException {
    JSONObject forecast = new JSONObject(jsonData);
    String timezone = forecast.getString("timezone");
    Log.i(TAG, "from JSON: " + timezone);

    JSONObject currently = forecast.getJSONObject("currently");

    CurrentWeather currentWeather = new CurrentWeather();
    currentWeather.setHumidity(currently.getDouble("humidity"));
    currentWeather.setTime(currently.getLong("time"));
    currentWeather.setPrecipChance(currently.getDouble("precipProbability"));
    currentWeather.setSummary(currently.getString("summary"));
    currentWeather.setTemperature(currently.getDouble("temperature"));
    currentWeather.setTimeZone(timezone);

    Log.d(TAG, currentWeather.getFormattedTime());

    return currentWeather;
}