Pasto sits at 2,500 m in the Andes, so the climate is cool year-round — daytime highs around 18 °C, nights down to 6 °C or lower. There is no real dry season, but the wettest months are March–April and October–November.
The big event is the Carnaval de Negros y Blancos in the first week of January, declared a UNESCO Intangible Cultural Heritage in 2009. Hotel rooms book out months ahead and the city goes nonstop for a week.