Raymond James Stadium is getting a new video board, but fans at Bucsnation who go to the games say they would much rather have shading structure. Read their comments here: New Video Board.
So if fans are fighting off the heat in September and on, then the heat and humidity must be more intense during the summer for the players to practice within. With the limited amount of teams in the NFL, it seems as though they are slow to create indoor practice facilities as many collegiate teams are using them to draw in prospective players.