Environmental variables play a crucial role in spreading several infectious diseases, particularly the vector-borne diseases, like, malaria and dengue. There are strong evidences on the regulatory role of environmental variables on the transmission and spreading of malaria and dengue across different parts of the world. Considering this background, the present research aims to evaluate the influences of atmospheric carbon dioxide, air temperature, relative humidity, and precipitation on two common vector-borne diseases, namely, malaria and dengue, based on the data bank of more than two decades (2001-2022). The work was carried out in two major districts of West Bengal (India), namely, Darjeeling and Canning located in the northern and southernmost parts of the state of West Bengal. Correlation carried out on the data sets showed significant positive influences of the environmental variables on both malaria and dengue in Canning, but the influences were not statistically significant in Darjeeling, which may be attributed to the topographical situations of the two sites.