Is ONE PIECE episode 609 filler?
Canon No, episode 609 of ONE PIECE is canon.
#609
Luffy Dies from Exposure?! The Spine-chilling Snow Woman Monet!
ルフィ凍死！？恐怖の雪女モネ！
Aired 25 Aug 2013
Mochibayo compiled this list from MyAnimeList's labels, because MyAnimeList's episode data is not reaching us at the moment.