Anticipating a thundershower that would ultimately come within the hour and never let up, the grounds crew covered the field with a tarp after the national anthem and minutes before the scheduled 7:05 p.m. start.
With forecasters calling for rain the rest of the night, the game was called after a delay of more than three hours.
The game will made up on July 12 at a time to be announced later.
The two-game series was scheduled to conclude Wednesday afternoon under the threat of more rain.
Meeting for the first time since 2015, the Phillies and Orioles both won five of their previous six games. After a 17-1 rout of Tampa Bay on Sunday, Baltimore (13-28) had back-to-back series wins for the first time this season.
Led by Manny Machado, the Orioles have finally started hitting after opening the season in a prolonged slump at the plate. Machado entered play Tuesday tied for the AL lead in homers (13) and was second with a .350 batting average.
Machado's hot streak has caught the eye of Phillies manager Gabe Kapler, even if it's happened entirely in the other league. The first-year manager ranked the Orioles shortstop among the league's five or 10 best players.
''He's an animal,'' Kapler said. ''He hits just about everything in the strike zone. When he's going good, he hits things out of the strike zone as well.''
The same can be said for Phillies center fielder Odubel Herrera, who has reached base in a career-best 41 straight games dating back to last year. He came in with a .360 batting average, second-best in the big leagues behind Boston's Mookie Betts (.362).
With a victory in its next game, Philadelphia (23-16) would climb eight games over .500 for the first time since the end of the 2011 season.
The Phillies are 3-0 in interleague play, pulling off a sweep of host Tampa Bay last month. This series launches Baltimore's foray into interleague play.
Phillies: After appearing in 27 games a year ago, RHP Mark Leiter Jr. (forearm) returned from the 10-day DL and was ready to make his season debut for the club in a ''jack of all trades'' relief role, according to Kapler. ... Jerad Eickhoff (back muscle) allowed three runs and five hits in 3 1/3 innings in a rehab start for Double-A Reading. The injury occurred in spring training. ... Reliever Victor Arano (rotator cuff), placed on the 10-day DL on April 29, may be activated on Wednesday, Kapler said. ... LHP Adam Morgan (back) will likely rejoin the club on Thursday when he is eligible to return from the 10-day DL.
Orioles: Closer Zach Britton (Achilles tendon) is ''getting close'' to beginning a rehab assignment, manager Buck Showalter said. ... RHP Darren O'Day (elbow) won't be activated from the DL on Wednesday when he's eligible to return, but he will be ready ''not long after that,'' Showalter said.
More AP baseball: www.apnews.com/tags/MLBbaseball
Copyright 2018 by AP. Any commercial use or distribution without the express written consent of AP is strictly prohibited.