Wanna go to Rio, De Janiero?

Qantas is offering a range of earlybird specials for 2016. They are particularly championing those to Japan, but this business class one to South America took my eye. Depending on when you travel, its nearly half price compared to the fare at peak times – $4,500 rather than closer to $9,000 if you travel March to July 2016. I think there might be something happening in August though. What could that be?