In general the climates in Bolivia are dictated mostly by altitude not latitude. The basic weather pattern of Bolivia is the wet and the dry season, which happens at the same time country-wide. There are basically five separate climatic regions: The Andes and Altiplano, the Yungas and Chapare, the temperate valleys, the Chaco and the tropical lowlands of the upper Amazon basin.
Andes and Altiplano: In the highland region, located in the western third of the country, the weather does not change too dramatically from season to season. In general it’s a cold weather region because of its geographical location and the weather patterns that affect it. It has been said that in the Andes one can experience all seasons in one day. During the night, it’s cold like Winter, in the early morning, it’s like an early Spring, during the day it’s like a hot Summer and in the late afternoon it’s like a crisp Autumn day. The weather can be hot during the winter days (May to September) but can get bitterly cold at night, and well below freezing the further south you go. During the wet season (December to March) it will be cold when it rains but can be very pleasant during the day when the sun is out and the nights can be mild.
The Yungas and Chapare: The Yungas and Chapare regions are the eastern side of the Andes that are between the high Andes mountains and the upper Amazon basin. The geography for the most part is steep and rugged with a lot of jungle and whitewater rivers, which are abundant. This region is generally hot and humid and the climate does not change much during the year, except when the rains come during the wet season (December through March). During the dry season it rains less but it’s still hot and humid.
The Temperate Valleys: These valleys are generally concentrated in the central and south-central part of the country have some of the most pleasant climates in the country. The geographic variety of the rolling hills and temperate climate made this region a favorite for the Spaniards during the colonial era. They characteristically don’t have the extremes temperature changes that occur daily or seasonally in other regions. The climate is mild and mediterranean-like with warm to hot days and pleasant night-time temperatures. This region is where the majority of the fruits and vegetables come from and which are distributed country-wide.
The Chaco Scrub and Plains: In general the Chaco is known as the desert of Bolivia. It is generally flat with some rolling hills and valleys and a few rivers that drain the sparse landscape. Most of the plants have adapted to the very hot temperatures and low humidity that this region is known for. Short bushes, thorny branches, coarse grasses and cactus make up the majority of the plant life with a few scattered large trees. Since it’s so inhospitable few people live here and so the abundance of wildlife is varied and abundant. Hot, dusty and dry would describe the Chaco except in the rainy season when it’s hot and the dust turns to mud.
Seasonal Temperatures: Once again, it depends on where you are in the country. During the dry season (the winter time) temperatures are generally colder and can be downright freezing in the highlands (and well below freezing the further south you go ) and it can be pleasant in the lowlands. The wet season (the summer time) brings hot temperatures and humid conditions to the tropics and cold and wet conditions to the highlands. In the middle altitudes (the valley region) temperatures don’t change in extremes like the highlands and lowlands. Winter has the most beautiful climate and temperatures in the valley regions.
Best Seasons for Travel: There are primarily two seasons in Bolivia – the dry and the wet. The dry season is from May to October, the winter time months. The wet season is from November to April, the summer time months. It is coldest during the months of June to September and wettest from December to March. The dry season is best for travel due to the better road conditions and generally sunny skies and warm temperatures during the day. Travel to most regions of Bolivia is certainly possible year round but you must be prepared to deal with the seasonal changes (as in most countries that experience severe seasonal weather changes) and their effects on weather patterns and the subsequent roaand atmospheric conditions.
The Tropical Lowlands: These regions, which make up most of the Bolivian territory are composed of the upper Amazon basin in the north and northeast regions and the Parana basin in the east and south-east region. These tropical lowlands have a variety of ecosystems and in general they are hot and humid year round. During the rainy season (December to March) the rain is constant and torrential downpours are the norm. It will rain probably everyday during the wet season and flooding is a normal part of the process. The rainforest ecosystem depends on the seasonal flooding to function normally. Hot and humid would describe the lowlands’ climate. But, there are bitterly cold winds that come up (called Surazos) from Patagonia and the Argentine pampas that can drop the temperatures 30-40 degrees for days on end.
Rainfall: The wet season country-wide is from late November to late March or early April, depending on where you are geographically. The quantity of rainfall varies from region to region, but the tropics get most of the rain by far. It can rain any day of the year in the Yungas and parts of the tropics as well. The highlands get very little rain in the winter except when it snows or hails, which are more frequent in the summer – wet season.
Bolivia is made up primarily of six regions: The Andes, the Altiplano, the Yungas, the highland valleys, the Gran Chaco, and the tropical lowlands of the Parana and Amazon basins.
The Andes: Two major branches of the Andes make up Bolivia’s mountain territory. One, starting in the Nudo de Apolobamba (north of L. Titicaca and on the Bolivia-Peru border) heads generally south and south-east, east of Lake Titicaca, east of La Paz and continues south on the eastern edge of the Altiplano and continues into northern Argentina. This section is primarily made up of the Cordillera de Apolobamba, Cordillera Real and Cordillera Quimsa Cruz. These are steep and rugged mountains with permanent snow, glaciers and the origin of many whitewater rivers that primarily head to the eastern side of the Andes known as the Yungas. The mountains rise to over 21,300 ft and average between 17 and 19,000′. Without a doubt the most spectacular ranges in Bolivia. The other branch encompasses the Cordillera Occidental (Western Range) and has many isolated summits made primarily of volcanoes and makes up the western border of the country and heads south and continues into Chile. This is where Sajama (Bolivia’s highest peak at 21,465′) lies near the Chilean border and borders the Altiplano on the west.
The Altiplano: Altiplano means high plain but in reality it’s not very flat and is made up of valleys, small hills and rolling areas as well as salt flats, volcanoes, rivers and lakes. It runs from north of Lake Titicaca, between the two branches of the Andes, heads south and into northern Argentina and Chile. It is roughly 900 km (560 mi.) in length and about 200 km (125 mi) wide. It is generally cold and windy and mostly treeless. The vegetation is sparse and mostly made of tough clumps of grass called ‘ichu’, short and tough Thola bushes and occasional stands of native trees called Quenua. It has the world’s biggest salt flat (Salar de Uyuni) and various others as well as Red and Green lagoons in the south. Many volcanoes lie scattered among the plains and mesas and their volcanic flows have been shaped into a maze of canyon-lands by the erosive powers of rain, wind, snow and hail over eons. Roads are few and rugged and no reliable gas or services are readily available. This landscape is quite rugged, has limited but interesting flora and fauna and beautiful as well.
The Yungas: This is the eastern side of the Andes and is primarily the steep jungle-covered mountains that head east and eventually meet with the tropical eastern lowlands. They are rugged and largely undeveloped due to their geographic and geologic characteristics. The upper reaches are made of cloud forests and the rivers that cascade of the high glaciated summits cut their way through this region and empty into the upper Amazon Basin. They are rich in flora and fauna and some of Bolivia’s most spectacular parks are located here. They are criss-crossed with Inca trails and were the only access into the lowlands for thousands of years. The development of a few roads in the 1930s and 40s and shortly a modern highway and the ensuing infrastructure will help develop this region quite fast. This region provides the bulk of fruits and vegetables for the highlands and is the region where the ancient coca plant is cultivated. The climate is hot and there is a lot of rain, especially in the summer time. For tourists, this is one of the major regions for trekking, rafting and nature tours and for gaining overland access to the lowlands.
The Highland Valleys: This region lies east and southeast of the Altiplano and has the most hospitable climate in the whole country. It is made up of the rolling hills, valleys and basins that are part of the Central Cordillera. The soils are fertile and the climate is Mediterranean-like, except that it rains in the summer (just like the rest of Bolivia) as opposed to the winter time. The second most populous region of Bolivia has the cities of Cochabamba, Sucre, Tarija and Potosi. Only Potosi has the disadvantage of being high in the mountains and doesn’t enjoy the nice climate of the others. This region is where a large majority of the colonial Spanish cities were founded and the huge mansions and estates are being renovated to accommodate more tourists for them to enjoy some of the past glory and charm of days gone by. Major roads connect all of these cities and a few modern highways have brought these areas into the 21st century only recently. In-country flights give easy access to these areas from cities across the country.
The Gran Chaco: This region is located in the south-eastern corner of the department of Santa Cruz. It borders with Argentina and Paraguay. It is characterized by being a harsh and almost impenetrable flat land of thick brush, cactus and grassy expanses with some forested areas. It’s generally hot and vey dry and a coat of dust (or during the rainy season – mud) covers everything. Being so harsh and isolated it provides one of the most diverse regions for wildlife (like peccary and jaguar) and flora and birds where they are not afraid of man. A lot of petroleum production also comes from this area. There are very few roads and harsh driving conditions without any services of any kind. Very few and isolated settlements are in this region. Villamontes is the only large town, situated on the railway and said to be Bolivia’s hottest spot, regularly in high 40s (C) /105-113 (F). A harsh but beautiful land.
The Tropical Lowlands: This region is made up of two major basins the Upper Amazon in the north and east and the Parana in the south-east. In the north lies the vast savannahs, thick jungles and broad rivers of the Beni, Pando and La Paz departments. In the East lies the grasslands and jungles of Santa Cruz and in Cochabamba lie the jungles and rivers of the Chapare region. Where Cochabamba and Santa Cruz meet is the elbow of the Andes and it offers a whole range of ecosystems from high mountains and cloud forests to semi-tropical valleys and thick jungles and rivers. Amboro and Carrasco National Parks are located here. All of this region offers hot and humid climate with rain possible anytime of the year. Truly a bountiful land of flora and fauna and indigenous forest people who are dwellers of the fragile Amazon basin. Noel Kempf Mercado National Park is located in the northeastern tip of Santa Cruz and the Chaco is also another National Park. Unfortunately, this region is also where the majority of the trees for the timber industry are being cut down and the forests being destroyed.