Storm Harpies appear to be roughly human, with the torso, head, and legs of a teenage girl. They have pale, bluish skin and teal hair. Where their arms should be, they have large blue feathered wings.Instead of feet, they have bluish talons.
Their outfits (though it may be their epidermis) consists of a purple, fur-lined bikini top and similarly decorated capris, though the capris have blue leopard print on them.
- The Storm Harpies resemble Lucy, from Cloud Tower. This is either a character error of Iginio Straffi's or an intentional pun fashioned by Stormy at Lucy's expense.
- The Harpies are creatures from Greek mythology depicted as women with wings or birds with the heads of women and who were sent to steal a king's food to keep him hungry for ever as a punishment from Zeus, the King of the Gods. They are the personification of the destructive nature of wind. The name comes from the Greek word for "snatcher".
- When the Winx first saw the Storm Harpies attacking them, Aisha said that she thought Storm Harpies only existed in fairy tales, to which Flora remarked that there are people who also think the same about Fairies.