In Rio de Janeiro the summer months (December and January) can be quite humid, with temperatures reaching into the mid 80’s, and this is the wettest time of year. Most of the precipitation during the summer months comes in the form of quick downpours lasting 1-2 hours before clearing up. During the winter months (June and July) the temperatures drop a bit to the mid-70s, with a mix of rain and sun. These weather conditions hold true for much of Brazil’s coastline north of Rio, with slightly higher temperatures in the northern cities such as Salvador, Recife and Fortaleza.
In São Paulo and to the south the climate has larger variations, with winter month temperatures often falling into the 40s and 50s.
The Pantanal, Brazil’s tropical wetlands, receive the most rain, with high precipitation throughout most of the year. The average temperature in the Pantanal is in the upper 70s, though it can fluctuate widely and temperatures over 100 F have been recorded in the summer. The Pantanal has a so-called “dry season” from May to September, during which time there is less rainfall and the water levels recede somewhat. The heaviest rains tend to fall in February and March.
Iguacu has a sub-tropical climate and is surrounded by rainforest, with temperatures varying from the 60s and 70s (June and July) up into the 80s and 90s (December and January). It is also an area of high precipitation. April to July is the period of least rain, and during this time the falls can diminish in size.
The Amazon receives the most rain, with high precipitation throughout most of the year (though relatively less in the “dry season” of approximately June through September), and temperatures consistently in the 80s and 90s.