All scores from Thursday will be taken off the board, with play beginning anew on Friday at 0545 GMT (1:45 a.m. ET).
"While we did not make this decision lightly, we believe that this is the right decision – to have the fairest, most competitive tournament for all players in this field," said LPGA Commissioner Mike Whan.
"We are happy and encouraged with how well the golf course is handling the weather, and it should set up for another amazing Evian finish."
After Saturday's play, a cut will be made and the top 70 players and ties will advance to the final round on Sunday.
(Reporting by Frank Pingue in Toronto; Editing by Toby Davis)