When does Star Wars Rebels return?

Star Wars Rebels is an animated science fiction television series set in the Star Wars universe. It takes place over a decade after Episode III: Revenge of the Sith and progressing toward the events of the original Star Wars film. The visual style of the series is inspired by the original trilogy concept art by Ralph McQuarrie. The series comprises four seasons. It premiered as a one-hour television film, Spark of Rebellion, on October 3, 2014, on Disney Channel prior to the premiere of the show on October 13 on Disney XD.
A motley group of rebels called the Spectres unite aboard a light freighter called the Ghost. The Spectres conduct covert operations against Imperial forces on and around the planet Lothal.