Topography in Bolivia ranges from 5,000 meters above sea level in the rugged highlands of the Andes Mountains, to Inter-Andean Valleys to the plains of the Amazonian and Chacoan lowlands, less than 500 meters above sea level. Thus, the country is split into three topographical/climatological regions: the Andean area and arid highlands of the west; the sub-Andean and semi-tropical valleys in the middle third of the country; and the tropical lowlands of the east. In most places, rainfall is heaviest in summer and yearly amounts tend to decrease from north to south. Temperatures in Bolivia depend on elevation and show little seasonal variation. Bolivia is also impacted by the El Niño Southern Oscillation (ENSO). La Niña events, for example, typically lead to cold fronts and heavy rainfall during the summer.
- Positive trends for the warm nights and negative trends for the cold nights have been observed.
- Since 1939, mean annual temperature has been increasing at a rate of 0.1°С per decade.
- Serious glacier retreat has been observed in the Bolivian mountains due to changes in temperature and humidity. Since the mid-1990s, the Chacaltaya glacier has lost half of its surface and two-thirds of its volume. Similarly, since 1940, the Charquini glacier has lost 47.4% of its surface area.
- Since 1970, mean annual precipitation has increased by 15% in the Bolivian Amazonia. The rainy season has shifted to a later date.
- A slight decline in the total volume of rainfall has been observed and monthly distribution has varied considerably, mostly from December to February.