Infinity Ward let PS4 owners pre-download the Season 5 update (which was 36GB) back in August, so it’s following suit here.
Pre-downloading is welcome, of course, but it’s unfortunate you can’t do it on PC and Xbox One. According to Activision: “Xbox does not support the ability to pre-download. Similarly, Battle.net does not currently support pre-downloads for Call of Duty: Modern Warfare or Warzone.”
Season 6, which launches at 7am UK time tomorrow, 29th September, adds fast-travel to Warzone via a new Metro system, as well as new operators, weapons and a fresh battle pass.