Durant completed 86-of-129 passes for 1,172 yards and nine touchdowns as Saskatchewan picked up wins in three of its four games.
He leads the CFL with 21 touchdown passes against just one interception for the Riders (8-1).
Meanwhile, Montreal Alouettes linebacker Chip Cox grabbed defensive player of the month honours.
Cox had a CFL-high 71 tackles, adding 32 to his tally in August to go along with one sack.
Saskatchewan kicker Chris Milo was named as the special teams player of the month after making all 11 field goals he attempted.
Montreal linebacker Marc-Olivier Brouillette was name the league's top Canadian for August. His league-leading four forced fumbles have set up a pair of defensive touchdowns this year and he has a career-best four sacks — good for second on the team.