Arsenal, Liverpool, Tottenham Hotspur and Everton currently occupy the top four in the league table, with champions Manchester United sitting eight points adrift of the leaders after six games.
"I think the league will be open until the end," Mourinho said in a press conference. "At this moment some teams are being helped by the fixtures, some are more difficult than others. Manchester United have the most difficult one, immediately followed by us.
"I think by the end of November, that is the moment we will find out somebody is in a little bit better situation than others. I think this season can go all the way, and I think that is good."
Chelsea, who are fifth in the standings, will take on Norwich City at Carrow Road on Sunday.