Due to its large size and varied topography, the climate of Brazil has a wide range of weather conditions, even though most of it is within the tropical zone - about 90% of it.
Having said that, unless you are in the southern part of the country, its climate experiments basically two seasons: the rainy (summer) and the dry season (winter).
Let's remember that Brazil is the largest country in South America (47% of the total or 8,514,877 sq km) and world's fifth largest, both in terms of population and geographical area.
Remember, however, that seasons in Brazil, for its location on the Southern Hemisphere, are the reverse of those of Europe and US:
Spring: September - December
Summer: December - March
Autumn: March - June
Winter: June - September
According to the Köppen climate classification system (Wladimir Köppen: 1846-1940) Brazil's climate comprises five major subtypes: equatorial, tropical, semiarid, highland tropical, and subtropical.
The equatorial or tropical rainforest climate is found 12 degrees North and south of the equator.
In fact, the equator traverses the mouth of the Amazon, a region hot and wet throughout the year with temperatures over 25 °C (77 °F) and annual precipitations between 1,750 millimeters (69 in) and 2,000 millimeters (79 in).
However, in the western Amazon and Belém area, rainfall can reach the 3,000 millimeters mark (118.1 in).
Despite its high precipitation level, the Amazon rainforest has a three to five month dry season.
The climate of Brazil in the Northeast has the hottest and driest weather conditions of all. Rainfall is scarse and during dry season - May to November - temperatures can reach over 38 °C (100.4 °F).
Below the Tropic of Capricorn - which crosses the country at the latitude of the city of São Paulo. - the climate of Brazil becomes temperate.
Rio's average is around 80°F (26°C), but can get oppressively hot - 100°F (38°C) and more - during the summer months (December to March).
The average high temperature in Rio de Janeiro in February is 29° C (84° F ), the average low in July (winter) is 17° C (63° F ).