Similar to many areas of the globe, South America is under a monsoon regime. The Amazon rain-forest is one of the regions critical for this regime, known as the South American Monsoon System (SAMS). Besides being crucial to the Earth’s carbon budget, the Amazon is also important for SAMS development. During SAMS onset, the trade winds intensify and a northwesterly low-level jet, known as the South American Low Level Jet (SALLJ), is formed east of the Andes. Moisture originating in the Atlantic Ocean is recycled and reinvigorated over the Amazon and carried by the SALLJ to continental and subtropical South America. In this project, we analyze the projected changes in precipitation and extreme events of rainfall over South America by the end of the 21st century using the CESM Large Ensemble Project (LENS). LENS is able to reproduce the important elements of the SAMS. We find that wet season rainfall is projected to increase over the east coast and central South America. The SALLJ is projected to become stronger, especially during late wet season, and carry more moisture to subtropical South America. As a result, moisture convergence between the SALLJ and the South Atlantic Subtropical High increases, creating the conditions to rainfall over Central and Southeastern South America. Meanwhile, Amazon is projected to become dryer during both dry and wet seasons. As a result, rain-forest productivity is reduced during late dry season in Southern Amazon. As vegetation struggles to save water, evapotranspiration, and consequently surface latent heat flux are reduced. These factors have been suggested as crucial to SAMS initiation and their reduction is responsible for a delay in SAMS onset by the end of the century. Extreme wet events are projected to become more frequent, especially over Northeastern Brazil, Southern Brazil and Uruguay. As dry season rainfall is reduced in all of the regions analyzed, drought events are projected to become more frequent and longer over both the wettest (Northern Amazon) and the driest (Northeastern Brazil) regions analyzed.