TORONTO, Oct 7 (Reuters) - The Canadian dollar weakened to a session low against the U.S. currency on Monday after data showed building permits dropped more than expected in August. The Canadian dollar was at C$1.0324, or 96.86 U.S. cents, weaker than Friday's close of C$1.0292, or 97.16 U.S. cents. The loonie fell as far as C$1.0334 immediately after the data was released.