Rain began falling just as Chicago's position players were about to take the field for a 2:20 p.m. ET start. It persisted on and off for about an hour, before there was a window of about 90 minutes without rain. But because of oncoming storms, officials opted not to take the tarp off the field at that time. A steady rain then began falling shortly before 5 p.m. and forced the postponement 35 minutes later.
A makeup date has not yet been announced, though it is expected to fall during the Pirates' trip to Chicago in late September. The Pirates and Cubs have a three-game, weekday series at Wrigley Field from Sept. 29-Oct. 1, which falls during Pittsburgh's final road trip of the season.
Ross Ohlendorf, who was scheduled to start Sunday's afternoon contest and had warmed up before the rain started, will now make the start for the Pirates on Tuesday. Monday's start will be made Kevin Hart, who had already been slated to open up the homestand. Ohlendorf will then be followed in the rotation by Paul Maholm (Wednesday), Charlie Morton (Friday) and Zach Duke (Saturday).
The Pirates finished their road trip 1-4 and on a four-game skid.
Jenifer Langosch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.