# Prepare your statement at the start of your program
my $ST = $DB->prepare(q{
   REPLACE INTO met_office_raw_data
      SET observation_datetime_utc   = ?,
          observation_datetime_local = ?,
          observation_datetime       = ?,
          station_id                 = ?,
          station_name               = ?,
          temp_c                     = ?,
          dewpoint_c                 = ?,
          humidity_rh                = ?,
          wind_dir_compass           = ?,
          wind_speed_mph             = ?,
          wind_gust_mph              = ?,
          visibility_metres          = ?,
          pressure_hpa               = ?,
          pressure_tendency          = ?,
          weather_type               = ?
});

while (....) {
   # Then for each reading, get the values
   my ( 
      $file_obs_datetime_utc, $file_obs_datetime_local,
      $file_obs_datetime,     $file_station_id,
      $file_station_name,     $file_temp_c,
      $file_dewpoint_c,       $file_humidity_rh,
      $file_wind_dir_compass, $file_wind_speed_mph,
      $file_wind_gust_mph,    $file_visibility_metres,
      $file_pressure_hpa,     $file_pressure_tendency,
      $file_weather_type 
   ) = get_my_data();

   # and write them to the table
   $ST->execute(
      $file_obs_datetime_utc, $file_obs_datetime_local,
      $file_obs_datetime,     $file_station_id,
      $file_station_name,     $file_temp_c,
      $file_dewpoint_c,       $file_humidity_rh,
      $file_wind_dir_compass, $file_wind_speed_mph,
      $file_wind_gust_mph,    $file_visibility_metres,
      $file_pressure_hpa,     $file_pressure_tendency,
      $file_weather_type 
   );
}

##</code><code>##

while (....) {
   # Then for each reading, get the values
   my @data_fields = get_my_data();

   # and write them to the table
   $ST->execute(@data_fields);
}