Due to the country’s immense size, Brazil’s climate is extremely varied. The Equator runs through the northern part of the country while the Tropic of Capricorn crosses through the south (running parallel to São Paulo). As you head from north to south, the temperature, humidity, and precipitation levels change greatly. Brazil boasts four distinctive climactic zones: subtropical, equatorial, tropical, and semi-arid.
Ninety percent of the country is situated in the tropical zone, where there is very little seasonal variation. Rain is frequent and temperatures range 25–35°C (77–95°F).
However, as you head south, seasonal variations become more distinct, resembling those of the continental United States and Europe, with hot, steamy summers and cool winters. In the southern states of Santa Catarina and Rio Grande do Sul, temperatures can plunge low enough to produce frost and even snow.
With the exception of the Sertão, which receives very little rainfall, the rest of the country receives a lot of rain. Although rains are common throughout the year, coastal regions have distinctive rainy seasons where downpours are daily occurrences and can even last for several days.
In the Southeast, violent downpours flood the streets of Rio and São Paulo in the summer months between December and March. In the Northeast, along the coast between Bahia and Pernambuco, rainy season generally coincides with the winter months between June and August. Rain is much less frequent in the permanently sunny states of Rio Grande do Norte and Ceará, where temperatures remain constant year-round.
Close to the Equator, Maranhão, and especially the Amazonian state of Pará, receive the most rain throughout the year, with annual averages of 3,500 mm (138 inches) in some parts. The rest of the Amazon, along with the Pantanal, receives a lot of rain as well, but both regions also have a more pronounced dry season that lasts from March to October.
© Michael Sommers from Moon Brazil, 2nd Edition