Weiss was recalled from Triple-A Louisville on Monday.
The Reds placed a pair of regulars on the disabled list Monday, so a spot opened up for Weiss to head to Cincinnati. The right-hander has just one Triple-A inning under his belt, but he produced a 2.89 ERA to go with nine saves at Double-A Pensacola last season. He'll likely get used in low-leverage situations in the big leagues, however.