The decision to call the game came after a wait of nearly 2 1/2 hours. Although it wasn't raining at the scheduled 1:35 p.m. start, a severe thunderstorm was in the vicinity and quickly made its way to Camden Yards.
The rain never stopped.
Baltimore was seeking a three-game sweep against the sagging Blue Jays, who have lost seven straight. The Orioles have won eight of 12 to stay in the playoff hunt.
The Orioles on Monday open a four-game series at home against the Chicago White Sox, the AL Central leaders. Rookie Wei-Yin Chen will start for the Orioles, and Sunday's scheduled starter, Chris Tillman, has been pushed back to Tuesday.
Baltimore did not reveal its scheduled starters for Wednesday or Thursday. Newcomer Joe Saunders, obtained in a trade Sunday with Arizona, could fill one of the spots. To get Saunders, a veteran left-hander, the Orioles gave up reliever Matt Lindstrom and cash considerations or a player to be named.
"We started discussions with Saunders a long time ago, during the summertime," said Dan Duquette, Baltimore's vice president of baseball operations. "This is the opportunity we were waiting for. It just came together over the weekend."
The game was supposed to mark the return of Toronto's Adam Lind, who in the starting lineup at the cleanup spot Sunday after being activated from the 15-day disabled list on Saturday night. Lind has not played since July 25 because of a mild back strain.
Toronto next heads to New York to play the Yankees on Monday night. The last-place Blue Jays are mired in a season-high, eight-game road losing streak.
The Blue Jays did not have any media availability after the rainout was announced.