Costs here are generally reversed when using our climate's terminology, for our summer is their winter and vice versa, our spring their autumn and vice versa. Using the USA terminology, winter (their summer) is the high season, and our summer (their winter) the low. Shoulder seasons are the same, only the terms being reversed.
Weather
To repeat: Their winter is our summer, and vice versa, so it may be that the best time to visit there is during our winter (their summer). Higher up in the mountains of South America, you can be in mid-summer (by their reckoning) and still not be too warm, as the altitude takes care of that. Down on the coasts, however, you can roast, so be careful. As is always the case, their spring and autumn may be best (our autumn and spring, respectively).
In the four popular tourist targets of Buenos Aires, Rio, Lima and Caracas, the average MAXIMUM temperature ranges from November through March (their summer) are between 76°F and 85°F. In their winter (our summer), average MAXIMUM temperatures in the four cities are between 57°F and 79°F.
Activities
Again, why come to South America unless it is to explore the foreign ambiance, the culture and the arts? If you want to stay indoors on a rainy day, check out the various museums around the continent, but, otherwise, look for important sites such as Machu Picchu or the Nazca Lines in Peru (both with hikes involved), the Iguacu Falls (boat trips) in Paraguay, or Lake Titicaca (more boating) in Bolivia. If you insist on the usual kind of outdoor activities, you can go jungle touring in Peru and Ecuador, surfing in Brazil and Argentina, skiing in Bolivia and Chile or go on wildlife safaris in Venezuela and Ecuador.
