Call to a member function bind_param() on boolean error with PDO

Question

I'm working on a function that tries to do an UPDATE query using PDO, when I run the following error message can anyone suggest what is wrong?:

Call to a member function bind_param() on boolean in... line 89

My Code :-

public function updateForecast($UID, $lat, lng) {
    $forecast = new Forecast('xxxxxxxxxxxxxxxxxxxxxx');

    $hub_forecast = $forecast->get($lat,$lng);
    $current_forecast = (is_object($hub_forecast) && isset($hub_forecast->currently)) ? $hub_forecast->currently : NULL;

    $temperature = (is_object($current_forecast) && isset($current_forecast->temperature)) ? ($current_forecast->temperature - 32) / 1.8 : '';
    $precipitation = (is_object($current_forecast) && isset($current_forecast->precipProbability)) ? $current_forecast->precipProbability : '';
    $humidity = (is_object($current_forecast) && isset($current_forecast->humidity)) ? ($current_forecast->precipProbability * 100) : '';
    $status = (is_object($current_forecast) && isset($current_forecast->summary)) ? $current_forecast->summary : '';
    $temperature_feels = (is_object($current_forecast) && isset($current_forecast->apparentTemperature)) ? ($current_forecast->apparentTemperature - 32) / 1.8: '';

    $sql = "UPDATE weather_data SET
        temperature = ?,
        precipitation= ?,
        humidity = ?,
        status = ?,
        temperature_feels = ?
        WHERE UID = ?";
    $stmt = $this->db->prepare($sql);
    $stmt->bind_param('ssssss', $UID, $temperature, $precipitation, $humidity, $status, $temperature_feels); // line 89
    $stmt->execute();
    $this->db->commit();
    $stmt->close();
}

// Running the query with lat/lng values (first parameter is an internal unique identifier)

 updateForecast('12356','52.490074299999996','-1.9119724');