Stranger Things was renewed for Season 3 way back in December 2017, and production is set to begin in April.
Show creators the Duffer Brothers have said that Season 3 will incorporate a time jump, much as the sophomore season did.
(Season 1 was released in July; Season 2 dropped just in time for Halloween, in October.)
While this hasn’t officially been confirmed, some Stranger Things superfan sleuths on the Internet have uncovered what might be character descriptions for new roles to be cast ahead of Season 3.