2,000 fans are set to make the journey from Nottingham to Ashton Gate to help boost the crowd.
Bristol City are currently fourth in the attendance figures for League One, with Forest clear in front with an average gate of 19,474.
City chief executive Colin Sexstone said: "Hopefully we can finish the season with a flourish and get a few more big attendances in, which is crucial to us. It goes without saying.
"We average just over 11,100 at the moment and that is fantastic considering the sort of season we have had."