Bolivia

Bolivia is named after Simón Bolívar, a Venezuelan leader in the Spanish American wars of independence. The leader of Venezuela, Antonio José de Sucre, had been given the option by Bolívar to either unify Charcas (present-day Bolivia) with the newly formed Republic of Peru, to unify with the United Provinces of the Río de la Plata, or to formally declare its independence from Spain as a wholly independent state. Sucre opted to create a brand new state and on 6 August 1825, with local support, named it in honor of Simón Bolívar.

The original name was "Republic of Bolívar". Some days later, congressman Manuel Martín Cruz proposed: "If from Romulus, Rome, then from Bolívar, Bolivia" (Spanish: Si de Rómulo, Roma; de Bolívar, Bolivia). The name was approved by the Republic on 3 October 1825. In 2009, a new constitution changed the country's official name to "Plurinational State of Bolivia" to reflect the multi-ethnic nature of the country and the strengthened rights of Bolivia's indigenous peoples under the new constitution.

=== Pre-colonial ===

The region now known as Bolivia had been occupied for over 2,500 years when the Aymara arrived; however, present-day Aymara associate themselves with the ancient civilization of the Tiwanaku Polity, which had its capital at Tiwanaku, in Western Bolivia. The capital city of Tiwanaku dates back as early as 1500 BC, when it was a small, agriculturally-based village.

The Aymara community grew to urban proportions between AD 600 and AD 800, becoming an important regional power in the southern Andes from La Paz. According to early estimates, the city covered approximately 6.5 square kilometers (2.5 square miles) at its peak, and had between 15,000 and 30,000 inhabitants. However, in 1996, satellite imaging was used to map the extent of preserved suka kollus (flooded raised fields) across the three primary valleys of Tiwanaku, with the results suggesting a population-carrying capacity of anywhere between 285,000 and 1,482,000 people.

Around AD 400, Tiwanaku went from being a locally-dominant force to a 'predatory' state, aggressively expanding its reach into the Yungas and bringing its culture and ways to new peoples in Peru, Bolivia, and Chile. Nonetheless, Tiwanaku was not a violent or domineering culture; to expand its reach, the state exercised great political astuteness, created colonies, fostered local trade agreements (which made other cultures rather dependent), and instituted state cults.

As rainfall gradually decreased, the stores of food supplies decreased, and thus the elites lost power. Tiwanaku disappeared around AD 1000. The area remained uninhabited for centuries thereafter.

Between 1438 and 1527, Incan Empire expanded from its capital at Cusco, gaining control over much of what is now the Bolivian Andes, and extending its control into the fringes of the Amazon basin.

The Spanish conquest of the Inca empire began in 1524 and was mostly completed by 1533. The territory now called Bolivia was known as Charcas, and was under the authority of Spain. Local government came from the Audiencia de Charcas located in Chuquisaca (La Plata—modern Sucre). Founded in 1545 as a mining town, Potosí soon produced fabulous wealth, becoming the largest city in the New World with a population exceeding 150,000 people.

By the late 16th century, Bolivian silver was an important source of revenue for the Spanish Empire. A steady stream of natives served as labor force under the brutal, slave conditions of the Spanish version of the pre-Columbian draft system called the mita. Charcas was transferred to the Viceroyalty of the Río de la Plata in 1776 and the people from Buenos Aires, the capital of the Viceroyalty, coined the term "Upper Peru" (Spanish: Alto Peru) as a popular reference to the Royal Audiencia of Charcas. Túpac Katari led the indigenous rebellion that laid siege to La Paz in March 1781, during which 20,000 people died. As Spanish royal authority weakened during the Napoleonic Wars, sentiment against colonial rule grew.

The struggle for independence started in the city of Sucre on 25 May 1809 and the Chuquisaca Revolution (Chuquisaca was then the name of the city) is known as the first cry of Freedom in Latin America. That revolution was followed by the La Paz revolution on 16 July 1809. The La Paz revolution marked a complete split with the Spanish government, while the Chuquisaca Revolution established a local independent junta in the name of the Spanish King deposed by Napoleon Bonaparte. Both revolutions were short-lived and defeated by the Spanish authorities in the Viceroyalty of the Rio de La Plata, but the following year the Spanish American wars of independence raged across the continent.

Bolivia was captured and recaptured many times during the war by the royalists and patriots. Buenos Aires sent three military campaigns, all of which were defeated, and eventually limited itself to protecting the national borders at Salta. Bolivia was finally freed of Royalist dominion by Marshal Antonio José de Sucre, with a military campaign coming from the North in support of the campaign of Simón Bolívar. After 16 years of war the Republic was proclaimed on 6 August 1825.

In 1836, Bolivia, under the rule of Marshal Andrés de Santa Cruz, invaded Peru to reinstall the deposed president, General Luis José de Orbegoso. Peru and Bolivia formed the Peru-Bolivian Confederation, with de Santa Cruz as the Supreme Protector. Following tension between the Confederation and Chile, Chile declared war on 28 December 1836. Argentina separately declared war on the Confederation on 9 May 1837. The Peruvian-Bolivian forces achieved several major victories during the War of the Confederation: the defeat of the Argentine expedition and the defeat of the first Chilean expedition on the fields of Paucarpata near the city of Arequipa. The Chilean army and its Peruvian rebel allies surrendered unconditionally and signed the Paucarpata Treaty. The treaty stipulated that Chile would withdraw from Peru-Bolivia, Chile would return captured Confederate ships, economic relations would be normalized, and the Confederation would pay Peruvian debt to Chile. However, the Chilean government and public rejected the peace treaty. Chile organized a second attack on the Confederation and defeated it in the Battle of Yungay. After this defeat, Santa Cruz resigned and went to exile in Ecuador and then Paris, and the Peruvian-Bolivian Confederation was dissolved.

Following the renewed independence of Peru, Peruvian president General Agustín Gamarra invaded Bolivia. On 18 November 1841, the Battle of Ingavi took place, in which the Bolivian Army defeated the Peruvian troops of Gamarra (killed in the battle). After the victory, Bolivia invaded Peru on several fronts. The eviction of the Bolivian troops from the south of Peru would be achieved by the greater availability of material and human resources of Peru; the Bolivian Army did not have enough troops to maintain an occupation. In the district of Locumba – Tacna, a column of Peruvian soldiers and peasants defeated a Bolivian regiment in the so-called Battle of Los Altos de Chipe (Locumba). In the district of Sama and in Arica, the Peruvian colonel José María Lavayén organized a troop that managed to defeat the Bolivian forces of Colonel Rodríguez Magariños and threaten the port of Arica. In the battle of Tarapacá on 7 January 1842, Peruvian militias formed by the commander Juan Buendía defeated a detachment led by Bolivian colonel José María García, who died in the confrontation. Bolivian troops left Tacna, Arica and Tarapacá in February 1842, retreating towards Moquegua and Puno. The battles of Motoni and Orurillo forced the withdrawal of Bolivian forces occupying Peruvian territory and exposed Bolivia to the threat of counter-invasion. The Treaty of Puno was signed on 7 June 1842, ending the war. However, the climate of tension between Lima and La Paz would continue until 1847, when the signing of a Peace and Trade Treaty became effective.

A period of political and economic instability in the early-to-mid-19th century weakened Bolivia. In addition, during the War of the Pacific (1879–83), Chile occupied vast territories rich in natural resources south west of Bolivia, including the Bolivian coast. Chile took control of today's Chuquicamata area, the adjoining rich salitre (saltpeter) fields, and the port of Antofagasta among other Bolivian territories.

Since independence, Bolivia has lost over half of its territory to neighboring countries. Through diplomatic channels in 1909, it lost the basin of the Madre de Dios River and the territory of the Purus in the Amazon, yielding 250,000 km2 to Peru. It also lost the state of Acre, in the Acre War, important because this region was known for its production of rubber. Peasants and the Bolivian army fought briefly but after a few victories, and facing the prospect of a total war against Brazil, it was forced to sign the Treaty of Petrópolis in 1903, in which Bolivia lost this rich territory. Popular myth has it that Bolivian president Mariano Melgarejo (1864–71) traded the land for what he called "a magnificent white horse" and Acre was subsequently flooded with Brazilians, which ultimately led to confrontation and fear of war with Brazil.

In the late 19th century, an increase in the world price of silver brought Bolivia relative prosperity and political stability.

During the early 20th century, tin replaced silver as the country's most important source of wealth. A succession of governments controlled by the economic and social elite followed laissez-faire capitalist policies through the first 30 years of the 20th century.

Living conditions of the native people, who constitute most of the population, remained deplorable. With work opportunities limited to primitive conditions in the mines and in large estates having nearly feudal status, they had no access to education, economic opportunity, and political participation. Bolivia's defeat by Paraguay in the Chaco War (1932–1935), where Bolivia lost a great part of the Gran Chaco region in dispute, marked a turning-point.

The Revolutionary Nationalist Movement (MNR) emerged as a broad-based party. Denied its victory in the 1951 presidential elections, the MNR led a successful revolution in 1952. Under President Víctor Paz Estenssoro, the MNR, having strong popular pressure, introduced universal suffrage into his political platform and carried out a sweeping land-reform promoting rural education and nationalization of the country's largest tin mines.

Twelve years of tumultuous rule left the MNR divided. In 1964, a military junta overthrew President Paz Estenssoro at the outset of his third term. The 1969 death of President René Barrientos, a former member of the junta who was elected president in 1966, led to a succession of weak governments. Alarmed by the rising Popular Assembly and the increase in the popularity of President Juan José Torres, the military, the MNR, and others installed Hugo Banzer as president in 1971. He returned to the presidency in 1997 through 2001. Torres, who had fled Bolivia, was kidnapped and assassinated in 1976 as part of Operation Condor, the U.S.-supported campaign of political repression by South American right-wing dictators.

The United States' Central Intelligence Agency (CIA) financed and trained the Bolivian military dictatorship in the 1960s. The revolutionary leader Che Guevara was killed by a team of CIA officers and members of the Bolivian Army on 9 October 1967, in Bolivia. Félix Rodríguez was a CIA officer on the team with the Bolivian Army that captured and shot Guevara. Rodriguez said that after he received a Bolivian presidential execution order, he told "the soldier who pulled the trigger to aim carefully, to remain consistent with the Bolivian government's story that Che had been killed in action during a clash with the Bolivian army." Rodriguez said the US government had wanted Che in Panama, and "I could have tried to falsify the command to the troops, and got Che to Panama as the US government said they had wanted", but that he had chosen to "let history run its course" as desired by Bolivia.

Elections in 1978 were marked by fraud and those in 1979 were inconclusive. There were coups d'état, counter-coups, and caretaker governments. Following the 1980 election, General Luis García Meza carried out a coup d'état. The Bolivian Workers' Center, which tried to resist the putsch, was violently repressed. More than a thousand people were killed in less than a year. Cousin of one of the country's most important narco-traffickers, García Meza favored the production of cocaine. After a military rebellion forced out García Meza in 1981, three other military governments in fourteen months struggled with Bolivia's growing economic problems. Unrest forced the military to convoke the Congress elected in 1980, and allow it to choose a new president. In October 1982, Hernán Siles Zuazo again became president, twenty-two years after the end of his first term of office (1956–1960).

In 1993, Gonzalo Sánchez de Lozada was elected president in alliance with the Tupac Katari Revolutionary Liberation Movement, which inspired indigenous-sensitive and multicultural-aware policies. Sánchez de Lozada pursued an aggressive economic and social reform agenda. The most dramatic reform was privatization under the "capitalization" program, under which investors, typically foreign, acquired 50% ownership and management control of public enterprises in return for agreed upon capital investments. In 1993, Sanchez de Lozada introduced the Plan de Todos, which led to the decentralization of government, introduction of intercultural bilingual education, implementation of agrarian legislation, and privatization of state owned businesses. The plan explicitly stated that Bolivian citizens would own a minimum of 51% of enterprises; under the plan, most state-owned enterprises (SOEs), though not mines, were sold. This privatization of SOEs led to a neoliberal structuring.

The reforms and economic restructuring were strongly opposed by certain segments of society, which instigated frequent and sometimes violent protests, particularly in La Paz and the Chapare coca-growing region, from 1994 through 1996. The indigenous population of the Andean region was not able to benefit from government reforms. During this time, the umbrella labor-organization of Bolivia, the Central Obrera Boliviana (COB), became increasingly unable to effectively challenge government policy. A teachers' strike in 1995 was defeated because the COB could not marshal the support of many of its members, including construction and factory workers.

In the 1997 elections, General Hugo Banzer, leader of the Nationalist Democratic Action party (ADN) and former dictator (1971–1978), won 22% of the vote, while the MNR candidate won 18%. At the outset of his government, President Banzer launched a policy of using special police-units to eradicate physically the illegal coca of the Chapare region. The Revolutionary Left Movement (MIR) of Jaime Paz Zamora remained a coalition-partner throughout the Banzer government, supporting this policy (called the Dignity Plan). The Banzer government continued the free-market and privatization-policies of its predecessor. The relatively robust economic growth of the mid-1990s continued until about the third year of its term in office. After that, regional, global and domestic factors contributed to a decline in economic growth. Financial crises in Argentina and Brazil, lower world prices for export commodities, and reduced employment in the coca sector depressed the Bolivian economy. The public also perceived a significant amount of public sector corruption. These factors contributed to increasing social protests during the second half of Banzer's term.

Between January 1999 and April 2000, large-scale protests erupted in Cochabamba, Bolivia's third largest city at the time, in response to the privatization of water resources by foreign companies and a subsequent doubling of water prices. On 6 August 2001, Banzer resigned from office after being diagnosed with cancer. He died less than a year later. Vice President Jorge Fernando Quiroga Ramírez completed the final year of his term.

In the June 2002 national elections, former President Gonzalo Sánchez de Lozada (MNR) placed first with 22.5% of the vote, followed by coca advocate and native peasant leader Evo Morales (Movement Toward Socialism, MAS) with 20.9%. A July agreement between the MNR and the fourth-place MIR, which had again been led in the election by former President Jaime Paz Zamora, virtually ensured the election of Sánchez de Lozada in the congressional run-off, and on 6 August he was sworn in for the second time. The MNR platform featured three overarching objectives: economic reactivation (and job creation), anti-corruption, and social inclusion.

In 2003, the Bolivian gas conflict broke out. On 12 October 2003, the government imposed martial law in El Alto after 16 people were shot by the police and several dozen wounded in violent clashes. Faced with the option of resigning or more bloodshed, Sánchez de Lozada offered his resignation in a letter to an emergency session of Congress. After his resignation was accepted and his vice president, Carlos Mesa, became president, he left on a commercially scheduled flight for the United States.

The country's internal situation became unfavorable for such political action on the international stage. After a resurgence of gas protests in 2005, Carlos Mesa attempted to resign in January 2005, but his offer was refused by Congress. On 22 March 2005, after weeks of new street protests from organizations accusing Mesa of bowing to U.S. corporate interests, Mesa again offered his resignation to Congress, which was accepted on 10 June. The chief justice of the Supreme Court, Eduardo Rodríguez, was sworn as interim president to succeed the outgoing Carlos Mesa.

Evo Morales won the 2005 presidential election with 53.7% of the votes. On 1 May 2006, Morales announced his intent to re-nationalize Bolivian hydrocarbon assets following protests which demanded this action. Fulfilling a campaign promise, on 6 August 2006, Morales opened the Bolivian Constituent Assembly to begin writing a new constitution aimed at giving more power to the indigenous majority.

2009 marked the creation of a new constitution and the renaming of the country to the Plurinational State of Bolivia. The previous constitution did not allow a consecutive reelection of a president, but the new constitution allowed for just one reelection, starting the dispute if Evo Morales was enabled to run for a second term arguing he was elected under the last constitution. This also triggered a new general election in which Evo Morales was re-elected with 61.36% of the vote. His party, Movement for Socialism, also won a two-thirds majority in both houses of the National Congress. By 2013, after being reelected under the new constitution, Evo Morales and his party attempted a third term as President of Bolivia. The opposition argued that a third term would be unconstitutional, but the Bolivian Constitutional Court ruled that Morales' first term under the previous constitution did not count towards his term limit. This allowed Evo Morales to run for a third term in 2014, and he was re-elected with 64.22% of the vote. During his third term, Evo Morales began to plan for a fourth, and the 2016 Bolivian constitutional referendum asked voters to override the constitution and allow Evo Morales to run for an additional term in office. Morales narrowly lost the referendum; however, in 2017 his party then petitioned the Bolivian Constitutional Court to override the constitution on the basis that the American Convention on Human Rights made term limits a human rights violation. The Inter-American Court of Human Rights determined that term limits are not a human rights violation in 2018; however, once again the Bolivian Constitutional Court ruled that Morales has permission to run for a fourth term in the 2019 elections, and this permission was not retracted. "[T]he country's highest court overruled the constitution, scrapping term limits altogether for every office. Morales can now run for a fourth term in 2019 – and for every election thereafter."

The revenues generated by the partial nationalization of hydrocarbons made it possible to finance several social measures: the Renta Dignidad (or old age minimum) for people over 60 years old; the Juana Azurduy voucher (named after the revolutionary Juana Azurduy de Padilla, 1780–1862), which ensures the complete coverage of medical expenses for pregnant women and their children in order to fight infant mortality; the Juancito Pinto voucher (named after a child hero of the Pacific War, 1879–1884), an aid paid until the end of secondary school to parents whose children are in school in order to combat school dropout, and the Single Health System, which since 2018 has offered all Bolivians free medical care.

The reforms adopted made the Bolivian economic system the most successful and stable in the region. Between 2006 and 2019, GDP grew from $9 billion to over $40 billion, real wages increased, GDP per capita tripled, foreign exchange reserves rose, inflation was essentially eliminated, and extreme poverty fell from 38% to 15%, a 23-point drop.

During the 2019 elections, the Transmisión de Resultados Electorales Preliminares (TREP) (a quick count process used in Latin America as a transparency measure in electoral processes) was interrupted; at the time, Morales had a lead of 46.86 percent to Mesa's 36.72, after 95.63 percent of tally sheets were counted. Two days after the interruption, the official count showed Morales fractionally clearing the 10-point margin he needed to avoid a runoff election, with the final official tally counted as 47.08 percent to Mesa's 36.51 percent, starting a wave of protests and tension in the country.

Amidst allegations of fraud perpetrated by the Morales government, widespread protests were organized to dispute the election. On 10 November, the Organization of American States (OAS) released a preliminary report concluding several irregularities in the election, though these findings were heavily disputed. The New York Times reported on 7 June 2020 that the OAS analysis immediately after the 20 October election was flawed yet fuelled "a chain of events that changed the South American nation's history".

After weeks of protests, Morales resigned on national television shortly after the Commander-in-Chief of the armed forces General Williams Kaliman had urged that he do so to restore "peace and stability". Opposition Senator Jeanine Áñez declared herself interim president, claiming constitutional succession after the president, vice president and both head of the legislature chambers. She was confirmed as interim president by the constitutional court who declared her succession to be constitutional and automatic. International politicians, scholars and journalists are divided between describing the event as a coup or a spontaneous social uprising against an unconstitutional fourth term. Protests to reinstate Morales as president continued becoming highly violent: burning public buses and private houses, destroying public infrastructure and harming pedestrians. The protests were met with more violence by security forces against Morales supporters after Áñez exempted police and military from criminal responsibility in operations for "the restoration of order and public stability".

In April 2020, the interim government took out a loan of more than $327 million from the International Monetary Fund to meet the country's needs during the COVID-19 pandemic. New elections were scheduled for 3 May 2020. In response to the coronavirus pandemic, the Bolivian electoral body, the TSE, made an announcement postponing the election. MAS reluctantly agreed with the first delay only. A date for the new election was delayed twice more, in the face of massive protests and violence. The final proposed date for the elections was 18 October 2020. Observers from the OAS, UNIORE, and the UN all reported that they found no fraudulent actions in the 2020 elections.

The general election had a record voter turnout of 88.4% and ended in a landslide win for MAS which took 55.1% of the votes compared to 28.8% for centrist former president Carlos Mesa. Both Mesa and Áñez conceded defeat.

On 8 November 2020, Luis Arce was sworn in as President of Bolivia alongside his Vice President David Choquehuanca. In February 2021, the Arce government returned an amount of around $351 million to the IMF. This comprised a loan of $327 million taken out by the interim government in April 2020 and interest of around $24 million. The government said it returned the loan to protect Bolivia's economic sovereignty and because the conditions attached to the loan were unacceptable.

On 26 June 2024, a military coup attempt led by Juan José Zúñiga ended after lasting only 5 hours. In the evening of 26 June, Bolivian police arrested Zúñiga.

In October 2025, Rodrigo Paz of the centre-right Christian Democratic Party (PDC) won the run-off race of the election against right-wing former president Jorge Quiroga, meaning the end of governance by the Movement for Socialism (MAS) party and a clear political shift to the right.

On 8 November 2025, Rodrigo Paz was sworn in as Bolivia's new president during Bolivia's worst economic crisis in 40 years.

Bolivia is located in the central zone of South America, between 57°26'–69°38'W and 9°38'–22°53'S. With an area of 1,098,581 square kilometers (424,164 sq mi), Bolivia is the world's 28th-largest country, and the fifth largest country in South America, extending from the Central Andes through part of the Gran Chaco, Pantanal and as far as the Amazon. The geographic center of the country is the so-called Puerto Estrella ("Star Port") on the Río Grande, in Ñuflo de Chávez Province, Santa Cruz Department.

The geography of the country exhibits a great variety of terrain and climates. Bolivia has a high level of biodiversity, considered one of the greatest in the world, as well as several ecoregions with ecological sub-units such as the Altiplano, tropical rainforests (including Amazon rainforest), dry valleys, and the Chiquitania, which is a tropical savanna. These areas feature enormous variations in altitude, from an elevation of 6,542 meters (21,463 ft) above sea level in Nevado Sajama to nearly 70 meters (230 ft) along the Paraguay River. Although a country of great geographic diversity, Bolivia has remained a landlocked country since the War of the Pacific. Puerto Suárez, San Matías and Puerto Quijarro are located in the Bolivian Pantanal. In Bolivia forest cover is around 47% of the total land area, equivalent to 50,833,760 ha of forest in 2020, down from 57,804,720 ha in 1990. In 2020, naturally regenerating forest covered 50,771,160 ha and planted forest covered 62,600 ha. Of the naturally regenerating forest 0% was reported to be primary forest (consisting of native tree species with no clearly visible indications of human activity) and around 24% of the forest area was found within protected areas. For the year 2015, 100% of the forest area was reported to be under public ownership.

Bolivia can be divided into three physiographic regions:

The Andean region in the southwest spans 28% of the national territory, extending over 307,603 square kilometers (118,766 sq mi). This area is located above 3,000 meters (9,800 ft) altitude and is located between two big Andean chains, the Cordillera Occidental ("Western Range") and the Cordillera Central ("Central Range"), with some of the highest spots in the Americas such as the Nevado Sajama, with an altitude of 6,542 meters (21,463 ft), and the Illimani, at 6,462 meters (21,201 ft). Also located in the Cordillera Central is Lake Titicaca, the highest commercially navigable lake in the world and the largest lake in South America; the lake is shared with Peru. Also in this region are the Altiplano and the Salar de Uyuni, which is the largest salt flat in the world and an important source of lithium.

The Sub-Andean region in the center and south of the country is an intermediate region between the Altiplano and the eastern llanos (plain); this region comprises 13% of the territory of Bolivia, extending over 142,815 km2 (55,141 sq mi), and encompassing the Bolivian valleys and the Yungas region. It is distinguished by its farming activities and its temperate climate.

The Llanos region in the northeast comprises 59% of the territory, with 648,163 km2 (250,257 sq mi). It is located to the north of the Cordillera Central and extends from the Andean foothills to the Paraguay River. It is a region of flat land and small plateaus, all covered by extensive rain forests containing enormous biodiversity. The region is below 400 meters (1,300 ft) above sea level.

The geology of Bolivia comprises a variety of different lithologies as well as tectonic and sedimentary environments. On a synoptic scale, geological units coincide with topographical units. Most elementally, the country is divided into a mountainous western area affected by the subduction processes in the Pacific and an eastern lowlands of stable platforms and shields. The Bolivian Andes is divided into three main ranges; these are from west to east: the Cordillera Occidental that makes up the border to Chile and host several active volcanoes and geothermal areas, Cordillera Central (in some contexts also called Cordillera Oriental) once extensively mined for silver and tin and the relatively low Cordillera Oriental that rather than being a range by its own is the eastern continuation of the Central Cordillera as a fold and thrust belt. The eastern lowlands and sub-Andean zone in Santa Cruz, Chuquisaca, and Tarija Departments was once an old Paleozoic sedimentary basin that hosts valuable hydrocarbon reserves. Further east close to the border with Brazil lies the Guaporé Shield, made up of stable Precambrian crystalline rock.

The climate of Bolivia varies drastically from one eco-region to the other, from the tropics in the eastern llanos to a polar climate in the western Andes. The summers are warm, humid in the east and dry in the west, with rains that often modify temperatures, humidity, winds, atmospheric pressure and evaporation, yielding very different climates in different areas. When the climatological phenomenon known as El Niño takes place, it causes great alterations in the weather. Winters are very cold in the west, and it snows in the mountain ranges, while in the western regions, windy days are more common. The autumn is dry in the non-tropical regions.

Llanos. A humid tropical climate with an average temperature of 25 °C (77 °F). The wind coming from the Amazon rainforest causes significant rainfall. In May, there is low precipitation because of dry winds, and most days have clear skies. Even so, winds from the south, called surazos, can bring cooler temperatures lasting several days.

Altiplano. Desert-Polar climates, with strong and cold winds. The average temperature ranges from 15 to 20 °C. At night, temperatures descend drastically to slightly above 0 °C, while during the day, the weather is dry and solar radiation is high. Ground frosts occur every month, and snow is frequent.

Valleys and Yungas. Temperate climate. The humid northeastern winds are pushed to the mountains, making this region very humid and rainy. Temperatures are cooler at higher elevations. Snow occurs at altitudes of 2,000 meters (6,600 ft).

Chaco. Subtropical semi-arid climate. Rainy and humid in January and the rest of the year, with warm days and cold nights.