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Southeast Arizona Climate

Southeast Arizona has a unique range of climates induced by a complex topography. The generally arid region is punctuated by an 'archipelago' of discrete mountain ranges that induce higher amounts of precipitation and experience much cooler annual temperatures than the low desert floors. These 'sky islands' support biotic communities typically found at much higher latitudes. Plant communities can vary from a desertscrub at lower elevations to spruce-fir forests at the highest elevations of a 'sky island'.

The average total annual precipitation for the region is 39.5 cm while the annual average temperature is 16.9^oC. These values represent the average conditions for Pima, Cochise, Santa Cruz, and Graham counties in SE AZ. Precipitation and temperature values vary considerably between the low desert areas and the sub-alpine environments of the mountain ranges. Temperature decreases with height on average in the lower atmosphere(link to explanation), so higher elevation areas will experience lower average temperatures than the low desert areas. Precipitation typically increases with elevation in mountainous areas due to a process called orographic lifting.

The role of topography in controlling surface climate is well illustrated in examining climate data from two weather stations located close to each other, but at different elevations. Weather stations at Tucson International Airport and Palisades Ranger Station are located within 40 km of eachother, but differ over 1600 m in elevation (topo map of Catalina-Rincon Venue with locations noted). This difference in elevation accounts for the dramatic differences in temperature and precipitation shown in the table and figures below.

Data from WRCC

The variations in temperature and precipitation with elevation can be further explored for SE AZ by examing high-resolution climate maps of the area. Note the patterns of temperature and precipitation as they relate to high and low elevation areas:
Links to DayMet Maps

References:

Sheppard PR,Comrie AC, Packin GD, Angersbach K, Hughes MK, 2002. The climate of the US Southwest. CR 21:219-238

Warshall, P. Southwestern Sky Island Ecosystems. http://biology.usgs.gov/s+t/frame/r119.htm