Brazil, a country of continental scale, experiences seasons defined more by proximity to the equator than by traditional temperature shifts found in higher latitudes. Its immense size, spanning from the equatorial Amazon in the north to areas below the Tropic of Capricorn in the south, creates a diverse range of climatic conditions. The concept of “season” changes across its territory, primarily shifting between a pattern of temperature and rainfall cycles and a more familiar four-season model. The majority of the country divides the year into a distinct wet period and a dry period, with temperatures remaining consistently high.
Understanding the Tropical Wet and Dry Cycle
For the majority of Brazilian territory, including the Amazon Basin, the Central-West (Cerrado), and much of the Northeast, the year is divided into two major periods rather than four seasons. This tropical wet and dry pattern, also known as a savanna climate, is characterized by minimal temperature variations compared to dramatic changes in precipitation. The difference between the hottest and coolest months is often only a few degrees Celsius.
The rainy season, often called the “tropical summer,” brings high heat and intense humidity, typically running from December to March. The air is thick with moisture, and heavy rainfall often occurs in the late afternoon as intense, but usually brief, showers. This abundance of water supports the lush ecosystems of the Amazon and the seasonal flooding of the Pantanal.
Conversely, the dry season, or “tropical winter,” generally extends from June to September across the central plateau. While temperatures remain warm, humidity levels drop significantly, and rainfall is scarce. This period is characterized by clearer skies, sunnier days, and noticeably cooler nights, particularly in higher elevation areas like Brasília. In regions like the Cerrado, the dry spell is pronounced, sometimes leading to drought conditions and an elevated risk of wildfires.
The Amazon region presents a slight variation, qualifying as an equatorial climate that is hot and humid year-round with constant rain. Even in the Amazon, a three- to five-month period of comparatively less rain is observed, often called the “dry season” by locals, although rainfall totals remain high. This emphasizes that for most of Brazil, the seasonal definition hinges on precipitation volume rather than a drop in temperature.
The Temperate Exception in Southern Brazil
A distinct climatic regime exists in the three southernmost states—Paraná, Santa Catarina, and Rio Grande do Sul—which lie south of the Tropic of Capricorn. This region experiences a humid subtropical climate where the difference between seasons is determined by temperature, much like in parts of North America or Europe. Here, the four distinct seasons of spring, summer, autumn, and winter are recognizable.
The winter months (June to September) are noticeably cool, with average temperatures in July oscillating between 10 and 15 degrees Celsius across the plateau. Cold air masses originating from Antarctica can push temperatures to near or below freezing, leading to frequent frost in higher-altitude areas. Snowfall, while rare, occasionally occurs in the mountainous regions of Santa Catarina and Rio Grande do Sul.
Summer (December to March) is hot, with average maximum temperatures in the lower areas reaching between 30 and 32 degrees Celsius, similar to the tropical north. Rainfall is well-distributed throughout the year, meaning this region lacks the absolute dry season that defines tropical areas. The transition seasons of autumn and spring exhibit mild temperatures and changing foliage, contrasting with the consistent greenery of the tropical zones.
The southern climate is characterized by a significantly wider range of temperatures throughout the year compared to the rest of the country. This temperate zone supports different ecosystems and agricultural practices, and the seasonal changes affect daily life in ways the tropical majority of Brazil does not experience. This regional split highlights the climatic diversity within the country.
Seasonal Calendar and Monthly Variations
Brazil’s seasons align with the Southern Hemisphere’s solstices and equinoxes. For the vast tropical and equatorial regions, the wet season generally begins in December and lasts through March, coinciding with the austral summer and bringing the highest heat, humidity, and rainfall across the Central-West and Southeast. The dry season typically starts in June and continues through September (austral winter), bringing the lowest precipitation totals. These dry months often offer the most comfortable conditions for travel in the interior, such as the Pantanal and Cerrado. The shoulder months of April/May and October/November mark the transition periods.
In the temperate South, the calendar follows the traditional four-season model based on temperature. Summer runs from December to March, and winter occurs from June to September, bringing the coolest temperatures and the highest chance of frost. Spring begins in September, and autumn starts in March, offering mild conditions during the transition between temperature extremes.