Fluctuation in the climatic factors influences not only the human health but also affect the abundance of disease vectors as well as infectious diseases. In the present study an attempt has been made to establish the relationship between Aedes mosquito abundance, dengue fever cases and prevailing climatic factors in the western region of Saudi Arabia. The role of Relative humidity is well established in the abundance of mosquito vector. But the role of temperature & rainfall is unpredictable in this area of study.