The WORLD GUIDE says:

"Just like North America, conditions on the South American continent vary greatly between east and west. It’s equally obvious that the west coast is oriented towards the front-side and the east coast the tail-end of weather systems. Most of all though, opposing ocean currents make for dramatic climatic differences that in turn immensely influence the winds. While the Brazil Current on the east coast feeds warm water southward, the Humboldt Current carries cold water from Antarctic waters way north along the west coast. Below 40° South the water’s bound to be... " world guide