Packing for weather in the rainforest

I'm getting my luggage sent to the airport ahead of me so I don't have to take it on the train. They are picking up my bag in about 3 hours and I'm still trying to figure out what exactly one should wear in the rain forest.
Apparently, June is the best month to go to Manaus since it is considered the start of the "winter" season in the Southern Hemisphere, so considerably less rain. Of course, we're still talking about the Amazon here, so that means the difference between average rainfall of 260mm in March and about 80mm in June. TripAdvisor.com describes Manaus' weather as "hot and wet" or "hot and humid", and I'll be there during the later, which BBC says is "highly" uncomfortable. Regardless, the Amazon River is supposed to look amazing this time of year, and Manaus is located where the Rio Negro and the Rio Solimoes meet. This is a famous spot to see the two rivers meet, which is obtusely visible due to the different temperatures of the waters where they meet, hence:
This should be fairly impressive to see in person and I'm looking forward to it. Still, I'm clueless on what to pack, but I'd better get to it!