In the Pantanal Wetlands, the weather is perfect for wildlife; with less water around, more animals congregate around the rivers to drink. Jaguars can often be seen drinking, resting and play fighting on the river banks; you may be lucky enough to see them swimming in the river. Other wildlife you can see in the Pantanal include anteaters, capybara, caiman and hyacinth macaws.
In the Amazon, you can expect similar temperatures to the Pantanal, and the wildlife encounters can be at their best. However, note that the Amazon is far denser than the Pantanal, so wildlife sightings can be harder, but very rewarding. Other activities in the Amazon include fishing for piranha and night walks, as well as 4x4 safaris and kayaking.
This is a great time to visit Rio de Janeiro as the spring is on its way. Temperatures are lovely and warm, and skies are mainly clear; so the beach can be a great option at this time too.