Climate
The Köppen classification depends on average monthly values of temperature and precipitation. The most commonly used form of the Köppen classification has five primary types labeled A through E. These primary types are A) tropical, B) dry, C) mild mid-latitude, D) cold mid-latitude, and E) polar. The five primary classifications can be further divided into secondary classifications such as rainforest, monsoon, tropical savanna, humid subtropical, humid continental, oceanic climate, Mediterranean climate, desert, steppe, subarctic climate, tundra, and polar ice cap.
Sonora
There are four major climate regions in the state: dry desert (Köppen "BW"), arid lands ("BS"), semi moist lands, and temperate zones ("Cwb"). Ninety percent of the state has desert or arid conditions. The other two climates are restricted to the areas of the state with the highest altitude such as the Yécora area, the mountains north of Cananea and a strip along the southeast of the state on the Chihuahua border.