When does Star Wars Rebels return?

Star Wars Rebels is an animated science fiction television series produced by Lucasfilm Animation. It takes place 14 years after Star Wars: Episode III – Revenge of the Sith (2005) and progresses toward the events of the original film. The visual style of the series is inspired by the original Star Wars trilogy concept art by Ralph McQuarrie. The series comprises four seasons.
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.