A temporal observational study on culicid entomofauna was conducted in a region characterized as a fragment of the Atlantic Forest that forms the Tingua´ Biological Reserve in the State of Rio de Janeiro. This investigation was performed with the aim of analyzing the inßuence of climatic factors (temperature and relative air humidity) on the activity levels at different times of the day among mosquito species within the ecosystems that form the Tingua´ Biological Reserve. The abundance index and dominance coefÞcient were calculated in relation to 61 mosquito species that were caught at four sampling sites, in the mornings, afternoons, and evenings. The results revealed that culicid species were distributed with greater incidence during the two diurnal periods and that their preference for times of the day was directly inßuenced by the climatic variables analyzed. The latter acted as limiting factors for occurrences of mosquito species.