Malaria is strongly influenced by climatic factors because the emergence of the vector species of the mosquito (Anopheles) is limited by precipitation and temperature conditions. Previous models have tended to predict the short period of malaria transmission in semi-arid regions, corresponding to the rainy season, although the emergence of Anopheles and the incidence of malaria are observed all through the year. Recent studies have reported that the water supply from irrigation systems creates a suitable habitat for Anopheles mosquitoes and could help them survive in the dry season. We developed a new model based on the life cycle of the Anopheles mosquito while considering climatic factors as well as the irrigation scheme in order to quantitatively analyze the effect of the irrigation system on Anopheles emergence. We selected five extensively irrigated representative sites in India and Pakistan and observed the monthly Anopheles emergence at those sites. With no irrigation, the mosquito emergence period was approximately 50 days and the potential alternation of generations was approximately 3. With irrigation, the emergence period was 3–5 times longer and the potential alternation of generations reached approximately 11. These results coincided with those of the field experiments, suggesting that irrigation systems can lead to a growth in Anopheles emergence in semi-arid regions.