Colorado Springs’ perpetually sunny skies and dry air often lead visitors to assume it is a desert. The visual impression of brown, scrubby foothills leading up to the Rocky Mountains reinforces this perception. However, classifying a region’s climate requires a precise scientific assessment of temperature and precipitation, not just casual observation. This article uses established climatological criteria to explain why Colorado Springs is not a desert, but belongs to a distinct climate category.
Defining a Desert by Climatological Standards
The scientific community uses the Köppen climate classification system, a globally recognized framework, to categorize climates based on vegetation requirements. This system groups dry climates into the ‘B’ category, split into Arid (true desert) and Semi-Arid (steppe). The fundamental difference lies in the balance between precipitation and potential evapotranspiration (water loss through evaporation and plant transpiration).
A true desert, classified as Arid (BW), has extremely low annual precipitation, less than 50% of the calculated dry-climate threshold. This threshold is determined by the region’s average annual temperature and seasonal rainfall distribution. Typically, a true desert receives less than 10 inches (250 millimeters) of precipitation annually. In these conditions, evaporation severely exceeds moisture supply, preventing the survival of anything but specialized desert plants.
A semi-arid climate, designated as Steppe (BS), receives more moisture than a desert, but not enough to support dense forests. A region is classified as semi-arid if its annual precipitation falls between 50% and 100% of the calculated dry-climate threshold. This higher rainfall allows for the growth of short grasses and scattered shrubs, creating a grassland or steppe environment. This marks the boundary between a barren desert and viable grazing land.
Colorado Springs’ Official Climate Classification
Applying these international standards, Colorado Springs is scientifically categorized as a Cold Semi-Arid Climate (BSk) within the Köppen system. The “k” suffix indicates a cold climate, meaning the average annual temperature is below 64.4°F (18°C). This classification places the city firmly within the steppe category, not the true desert category.
The city’s average annual precipitation falls between 15 and 17 inches (380 to 430 millimeters). This moisture level is substantially higher than the threshold for a true arid desert. For example, the average of 16.2 inches (412.6 mm) annually is well above the 10-inch desert benchmark. This precipitation allows for the growth of the short grasses and shrubs characteristic of a steppe environment.
The BSk classification confirms that while the environment is water-stressed and experiences dry periods, it receives sufficient moisture to prevent it from becoming an arid desert climate. The region’s dry appearance results more from low humidity and high elevation than a complete lack of rainfall. The majority of the area’s moisture arrives during the warmer months, contributing to the growth cycle of native grasslands.
The Geographic Mechanism: Rain Shadow and High Elevation
Colorado Springs exhibits a dry climate due to its geographic location relative to the Rocky Mountains. The city sits on the leeward (downwind) side of the Front Range, near Pikes Peak, which creates the rain shadow effect. This effect is the primary mechanism dictating the region’s semi-arid conditions.
Prevailing winds across North America move from west to east, carrying moisture-laden air masses from the Pacific Ocean. When this air encounters the immense barrier of the Rocky Mountains, it is forced to rise sharply in a process called orographic lifting. The rising air cools, causing water vapor to condense and fall as rain or snow on the western (windward) slopes. This process strips the air mass of most moisture before it crests the peaks.
Once the dry air descends the eastern side of the mountains toward Colorado Springs, it compresses and warms adiabatically. This warming air has low relative humidity and actively absorbs moisture from the landscape rather than releasing it. This contributes to the dry climate of the eastern plains and foothills. The dramatic elevation change makes this rain shadow pronounced in the region.
The high elevation of Colorado Springs, approximately 6,171 feet (1,881 meters), also contributes to the dry appearance and temperature variability. While the rain shadow explains the lack of moisture, the elevation contributes to lower atmospheric pressure and strong winds. These factors accelerate evaporation and transpiration. This combination of blocked moisture and accelerated water loss creates the visually dry, high-altitude steppe environment. The resulting low humidity also contributes to the wide daily temperature swings.
Ecosystems That Thrive in the Semi-Arid Climate
The flora and fauna of the Colorado Springs area provide biological evidence that the region is a semi-arid steppe, distinct from a true desert. The dominant vegetation consists of drought-tolerant, but not fully xerophytic, plant communities. This environment is biologically richer than an arid zone, reflecting the higher precipitation levels.
The lower elevations and plains are defined by short-grass prairie and mixed-grass ecosystems, hallmarks of the semi-arid High Plains. Species like Blue Grama and Buffalo Grass flourish here, forming dense sod that requires more consistent moisture than the sparse growth found in deserts. These grasslands support grazing animals like bison and pronghorn, a key distinction from the life supported by arid sands.
As the terrain rises into the foothills, the vegetation transitions to scrubland and woodlands, including Ponderosa Pine forests and thickets of scrub oak. Ponderosa Pines, though resilient, require annual rainfall outside the range of a true desert to sustain their growth. The presence of these substantial trees and dense shrublands confirms that the environment supports a higher level of biomass than the sparse, specialized life forms of an arid desert. This transition reinforces the scientific classification of the region as a cold semi-arid climate.