Among the long – term records of hundreds of U.S. weather stations is at least one very interesting and certainly significant record of precipitation increase during the past 40 years. Urban reviews show the causes and the nature of a variety of urban climate impacts, the urban heat island (UHI), urban moisture, and urban wind flow, In particular. (UHI) cause pressure field deformation, buildings produce barrier effects, and large urban surface roughness length values increase surface frictional drag. During UHI periods inward directed country breezes that develop due to the urban thermal low produce speed maxima near urban centers. A theoretical study of the effect of urbanization on rainfall is made; the study is done by using a version of the Advanced Regional Prediction System (ARPS), model of the Center for Analysis and Prediction of Storms, University of Oklahoma. A two-dimensional (vertical cross-section) version of the model is used. Model simulations are used to analyze the urbanization effects on rainfall of a coastal city.