The common bean crop has limiting factors associated with production among which the behavior of atmospheric elements are decisive. This work was conducted from 1987 to 1989 in western El Salvador. Bean varieties 'Rojo de Seda' and APN 83 were planted during in the second cycle (sept-december). The objective of this work was to determine the influence of atmospheric conditions on the development ofthe bean plant and to determine the phonologic stages which serve as a base in the planning and execution of defense mechanisms for integrated management 01" this crop. The phonologic stages which were established were emergence, initial formation of branching, flowering, pod formation, pod filling and maturity. The necessary heat units for each phonological stage were: 12.89, 61.09, 89.08, 99.31, 114.97, and 157.74, respectively (base temperature of 18.9°C). The same variables expressed in days after planting had the Following values: 4.5, 18.3, 28.7, 31.8, 37.3 and 54.2 respectively. Precipitation was the atmospheric clement which influenced production and development of the crop the most The Frequency and distribution were more important than the total amount. Similar adverse effects are also created by warm sub humid tropical climates.