While the Philippines is no stranger to typhoons and tropical storms, Koppu has been particularly slow moving - trapped by Typhoon Champi, just east of Koppu - allowing it to dump rain for for days longer than usual, making flooding especially severe.
It is the second strongest storm to hit the archipelago this year, and the 12th so far this year.
In 2013, Typhoon Haiyan tore through the Philippines causing major destruction and leaving more than 7,300 people dead or missing.