Climate is the long-term, prevailing patterns in weather of an area. Weather includes temperature, precipitation, wind speed and direction, cloud cover, air pressure and humidity. Weather varies by the day or even the minute, but the changes in climate happen so gradually it is not as noticeable. Since temperature and precipitation vary by season, we represent the annual average climate using climatograms. To the right is a climatogram for the town of Salento in the Quindio department, in Colombia. Many of the treks to summit the Nevado del Tolima leave from Salento in order to begin in Valle de Cocora.

Climate varies by both latitude and altitude. Hiking from the Valle de Cocora to the nevado results in passing through tropical forest, then cloud forest, páramo, alpine tundra and then ice/snow. Plants and vegetation have evolved to be well-adapted for the type of climate where they can be found, producing a dramatic transitions as you continue climbing toward the nevado.

Plants are the basis of food webs that receive sunlight as their initial energy source. Animals and other organisms have evolved adaptations to interact and live with these plants. Between the climate, the vegetation and other organisms, and how these interact with each other create a complex ecosystem. However, as climate continues to rapidly change, vegetation in the mountains will shift toward higher elevations, gradually displacing species who live at the highest altitudes. Meanwhile the glacier on the volcano will continue receding, representing a loss in climate regulation as well.