On account of the frequent droughts hitting Taiwan in the recent years, the government and research organizations are urged to develop drought forecast and alert systems. However, problems such as no reliability of the software system, no prediction of timing progress, and the rising cost and maintenance fee would arise when developing such a large-scale disaster forecast information system. The main reason is that standard software developing model has not been used as the guiding principle. By introducing CMMI in combination with wireless sensor networks and embedded multimedia communications technology, this study designs and develops a realtime, mobile and integrated Drought Forecast and Alert System (DFAS). Based on the standard CMMI model, the specification analysis of the system requirements, the plan of project execution, and the procedure of system design and test of the DFAS software developing process, may provide related disaster-prevention information system design and development with references.