When to visit Brazil
Brazil is split into four distinct climatic regions. The coldest part, and the only part that ever gets actually 'cold', is the south and southeast, an area that extends from central Minas Gerais to Rio Grande do Sui. Here there's a distinct winter between June and September that's chilly but mild compared to European or North American winters. Only in Santa Catarina's central highlands does it actually snow.
The coastal climate is very good and so supports the majority of the population, who revel in a warm, tropical climate. 'Winter' is characterised by cloudy days and temperatures that dip below 25C and a rainy season sees tropical downpours occasionally result in flooding and landslides; in Rio and south of here, the rains last from October to January but come much earlier in the north east, when they last from April to July. However, even during these periods the weather will often be sunny, with the wet conditions restricted to short intense bursts.
The north east is too warm to have a winter, with temperatures consistently above 25C; in the interior this often soars to as much as 40C. Rain is irregular but heavy when it does fall.
In contrast, Amazonia is a steamy, humid jungle. Rainfall is regular although there is a clear dry season, with the heaviest downpours from January to May.
Given the generally temperate conditions, there is no bad time to visit Brazil. Perhaps avoid the highest temperatures and massed crowds around Carnival; high season runs from December to March and instead travel from April to November.