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Nestled in southwestern Colombia's Cauca Valley, Cali occupies a strategic position at the foothills of the Western Cordillera of the Andes, approximately 1,000 meters above sea level. This elevation moderates its tropical climate but traps pollutants in the valley basin. The city straddles the Cali River, part of the broader Cauca River system, with the Farallones de Cali mountains forming a dramatic western backdrop that influences local wind patterns. Cali serves as the economic hub of Valle del Cauca department, characterized by a distinct urban–rural gradient where dense urban cores transition to sprawling sugarcane plantations and industrial zones. The Yumbo industrial corridor, located just north of the city, emits substantial industrial pollution that drifts southward into Cali under prevailing winds. This geography creates a natural bowl effect, where surrounding mountains inhibit pollutant dispersion, especially during dry seasons when temperature inversions form. Agricultural burning in the surrounding Valle del Cauca plains adds regional haze, while urban expansion generates construction dust and vehicle emissions concentrated in the valley floor. Proximity to the Pacific Ocean brings moisture but limited cleansing winds, making topography the dominant factor in Cali's air quality challenges.

Cali's air quality follows a distinct seasonal rhythm shaped by its tropical rainforest climate with bimodal rainfall patterns. During the drier months of December through February, pollution peaks dramatically due to reduced precipitation that would otherwise wash pollutants from the air. These months experience frequent temperature inversions, where cooler air traps vehicle exhaust, industrial emissions from Yumbo, and smoke from sugarcane burning in the valley. Sensitive groups should avoid prolonged outdoor activity during this period, especially on windless mornings when haze accumulates. March to May bring the first rainy season, with afternoon thunderstorms that temporarily clear the air, though construction dust may persist during breaks in rainfall. June to August see a relative lull in pollution as moderate rains continue, making this period more favourable for outdoor exercise. September to November experience a second rainy season, but occasional dry spells can allow pollutant buildup, particularly from agricultural burning in preparation for new planting cycles. Throughout the year, volcanic ash from nearby Nevado del Huila can occasionally worsen air quality during eruptions. The lack of strong prevailing winds means pollution dispersal relies heavily on convective afternoon rains, creating daily cycles where mornings are poorest for air quality.