The Braves announced that the game will be made up Aug. 30.
Rain began falling a few minutes before the scheduled first pitch at 7:35 p.m. It was coming down heavily an hour later and was called at 9:56 p.m.
It marked the sixth postponement for the Cubs this season and their second against Atlanta, which won a makeup game 6-5 on Monday at Wrigley Field.
The new date will give the Cubs 23 straight games without an off day from Aug. 21-Sept. 12. Atlanta will have one off day, Aug. 27, during a 37-day stretch that goes until Sept. 13.
Jon Lester, Thursday's scheduled starter, will pitch Friday when Chicago begins a four-game series at Cincinnati. Kyle Hendricks and Jose Quintana will start in Saturday's doubleheader, though the order has yet to be determined. Yu Darvish will pitch on Sunday.
Max Fried, recalled from Triple-A Gwinnett to start Thursday when Mike Soroka went on the 10-day disabled list with right shoulder strain, will move to the bullpen.
Cubs manager Joe Maddon, eager to rest his bullpen, was pleased to have LHP Randy Rosario recalled from Triple-A Iowa before the game.
"They've been perilously close to being way overused the last week, so I had to sit them down for the night," Maddon said. "The bullpen has been fabulous, and I want to keep them fabulous."
Chicago relievers began the day ranked third in the NL with a 2.79 ERA, but Maddon doesn't want to keep relying so heavily this early in the season on Brian Duensing, Pedro Strop, Steve Cishek, Carl Edwards Jr. and Justin Wilson to set up closer Brandon Morrow. To make room for Rosario, INF David Bote was optioned to Iowa.
Atlanta manager Brian Snitker said there's a chance SS Dansby Swanson, on the disabled list with left wrist inflammation, could return to the lineup on Friday. Swanson went 2 for 4 in a rehab appearance Thursday at Single-A Rome.
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