Brazil’s climate encompasses a wide range of weather conditions over a vast area and varied topography, but most of the country is tropical. According to the Köppen system, Brazil has five main climate subtypes: equatorial, tropical, semi-arid, mountain tropical, temperate and subtropical. The different climatic conditions give rise to environments ranging from equatorial rainforests in the north and semi-arid deserts in the northeast to temperate coniferous forests in the south and tropical savannahs in central Brazil. Many regions have very different microclimates.
An equatorial climate characterises most of northern Brazil. There is no real dry season, but there is some variation in the time of year when it rains the most. Temperatures average 25°C, with greater variations between day and night than between seasons.
In central Brazil, rainfall tends to be seasonal, which is characteristic of a savannah climate. This region is the same size as the Amazon basin, but its climate is very different because it is further south at a higher altitude. In the interior of the Northeast, seasonal rainfall is even more extreme. This semi-arid region generally receives less than 800 millimetres of rain, most of which falls over a period of three to five months a year, sometimes less, resulting in long periods of drought. The Grande Seca (Great Drought) of 1877-78, the worst in Brazil’s history, caused about half a million deaths. An equally devastating drought occurred in 1915.
South of Bahia, near the coast, and further south in most of the state of São Paulo, the distribution of precipitation changes, with rainfall throughout the year. In the south, subtropical conditions prevail, with cool winters and average annual temperatures that do not exceed 18°C; winter frosts and snowfall are not uncommon in the higher areas.