Because of its capacity to infect human beings and domestic animals with a number of different viruses, the study of the mosquito Ochlerotatus albifasciatus (Macquart, 1938, (Diptera: Culicidae)) assumes great importance from the point of view of sanitation. It is a well-known fact that the abundance of this species peaks after drought periods in the provinces of Buenos Aires and Cordoba. This article aims at explaining the presence of the high abundance of adult O. albifasciatus in Buenos Aires city in February 2005. As no breeding immatures were recorded during the previous weeks, the most likely hypothesis was that mosquitoes entered the city from breeding sites located in the outskirts. Wind observations, the existing knowledge on this species biology, atmospheric dynamic models, and meteorological data were used to support this hypothesis and identify the sources.Mass transport of these individuals was apparently the consequence of a convective process. It was demonstrated that the occurrence of a convective process transported air masses from the periphery towards the City of Buenos Aires. Air-parcel trajectories, Ezeiza radar images, and the flood zones observed in satellite images indicated that the source was located in the lowlands of Ezeiza in the Rio Matanza basin, some 50 km to the southwest of the City. The evidence suggests that O. albifasciatus is transported by wind, and the trajectory models are a very useful tool to locate the sources of proliferation of these insects.