The Andes Mountains, the world’s longest continental mountain range, stretch over 7,000 kilometers along the western edge of South America, traversing seven countries from Venezuela to the southern tip of Chile and Argentina. Determining the temperature of the Andes is complex because this enormous range spans multiple climate regimes, from the tropical north near the Equator to the sub-Antarctic south. Temperatures vary drastically not only from north to south (latitude) but also from the base to the highest peaks (altitude). The climate is a complex mosaic where elevation and latitude work together to create diverse temperature conditions.
Altitude: The Primary Temperature Regulator
The most significant factor controlling temperature in the Andes is altitude, governed by the atmospheric lapse rate. As elevation increases, air pressure and density decrease, resulting in less air mass to trap heat. This thinner air radiates heat back into space more efficiently, causing temperatures to drop consistently with every meter gained in height.
The average rate of cooling, known as the environmental lapse rate, is approximately 6.5°C per 1,000 meters of ascent (or about 3.5°F per 1,000 feet). This means that for every kilometer climbed, the temperature drops by several degrees, regardless of latitude. While this is a general average, the actual lapse rate can vary depending on local conditions like humidity, sometimes ranging from 5.5°C to 6.5°C per kilometer.
Because of this mechanism, high-altitude regions are perpetually cold, even under the tropical sun. In the tropical Andes, the base may be hot and humid, but the summits remain snow-covered year-round due to the drop in temperature with elevation. This vertical temperature gradient is the most important mechanism making the Andes a cold environment.
Defining the Vertical Climate Zones
The steady temperature drop with altitude creates distinct vertical climate zones, traditionally classified using Spanish terms called tierras (lands). These zones visualize the temperature gradient from the tropical foothills to the icy summits. The lowest zone, Tierra Caliente (Hot Land), extends up to about 1,000 meters (3,300 feet), characterized by hot, humid, tropical climates with average temperatures between 24°C and 27°C (75°F to 80°F).
Above this is the Tierra Templada (Temperate Land), between 1,000 and 2,000 meters (3,300 to 6,600 feet). Temperatures here are moderate, ranging from 18°C to 24°C (65°F to 75°F), often called the “Land of Eternal Spring.” The next level is the Tierra Fría (Cold Land), spanning 2,000 to 3,500 meters (6,600 to 11,500 feet), where temperatures average between 10°C and 18°C (50°F to 65°F). This zone is one of the most densely populated in the Andes.
The zone above 3,500 meters (11,500 feet) is the Tierra Helada (Frost Land) or Páramo, where conditions are harsh and cold. Temperatures average between 0°C and 10°C (32°F to 50°F), with nighttime temperatures frequently dropping below freezing. The highest zone is the Tierra Nevada (Snow Land), which lies above the permanent snowline, where the climate is polar and dominated by ice and extremely low temperatures.
Latitudinal and Regional Temperature Shifts
While altitude dictates the vertical zones, the overall temperature is modified by the mountain range’s enormous latitudinal extent. The northern Andes, close to the Equator in countries like Colombia and Ecuador, experience minimal seasonal temperature change. High-altitude areas here have a stable, year-round cool climate, where coldness is mainly a function of elevation rather than seasonal shifts.
In contrast, the Southern Andes, particularly in Patagonia (southern Chile and Argentina), exhibit significant seasonal temperature variability. Being further from the Equator, they experience cold, snowy winters and milder summers. The central Andes (southern Peru, Bolivia, and northern Chile) are often semi-arid and feature greater variation between day and night temperatures, alongside a distinct wet season during the austral summer.
Coastal temperatures influencing the lower slopes are affected by the cold Humboldt Current flowing north along the Pacific coast. This current keeps the western slopes of the central Andes (Peru and northern Chile) drier and cooler than their eastern counterparts, which face warm, moist air from the Amazon basin. This regional variation means a 4,000-meter pass in Ecuador will be colder but more climatically stable than one at the same altitude in southern Chile.
Extreme High-Altitude Conditions and the Snowline
The most extreme cold is found at the highest elevations, specifically above the permanent snowline—the altitude where snow persists year-round. The height of this snowline varies dramatically along the range due to latitude and precipitation. In the tropical Andes of Ecuador and Colombia, the snowline is found at a high elevation, typically between 4,500 and 4,800 meters (14,800 to 15,700 feet).
Moving south, the snowline drops progressively, reaching about 4,500 meters on Aconcagua in Argentina, and decreasing dramatically to as low as 300 meters (980 feet) in Tierra del Fuego. This variation highlights that the most severe cold is not uniformly distributed but is a function of distance from the Equator combined with extreme altitude. Glaciers exist across various latitudes, but they descend to sea level only in the cold, wet southern regions.
At these extreme heights, temperatures are consistently below freezing, defined by intense diurnal temperature swings. The thin air allows for rapid heating during the day under direct sunlight but equally rapid heat loss after sunset, leading to a massive temperature difference between day and night. Furthermore, the combination of low temperatures and high winds produces a severe wind chill effect, making the cold conditions feel more intense.