Mosquitoes are temporary blood-sucking parasites involved in the circulation of pathogens of many dangerous vector-borne infections and invasions. The spread of diseases and their transmission depends on the climate, the rate of transmission of pathogens, and population dynamics. There are many methods for constructing models of both biological objects and infections and invasions directly. This article discusses the issue of constructing an analytical mathematical model of the mosquito population size depending on the influence of three factors: average monthly annual temperature, average monthly precipitation and average atmospheric pressure per year. The obtained analytical model makes it possible to evaluate the indfluence of all the selected factors on the number of mosquitoes, both individually and in sum. The greatest influence on the number of mosquitoes is exerted by the average monthly precipitation, which may be explained by the peculiarities of the biology and ecology of arthropods. In general, analytical models make it possible to control the monitoring of the number of mosquitoes not only in the Kaluga region, but also in territories with similar climatic and geographic data. Mathematical modeling of temporary ectoparasites (mosquitoes) makes it possible to predict outbreaks of parasitic vector-borne zoonotic diseases.