Reports of population blooms of the freshwater jellyfish (Craspedacusta sowerbii) in lakes across North American are becoming increasingly frequent. However, because they appear sporadically in space and time, their distribution ecology, and the environmental factors that trigger their proliferations are poorly understood. The objectives of the present study were to determine the spatial distribution of, and the environmental factors associated with, C. sowerbii blooms in Québec (Canada), with the goal of better predicting future blooms of this exotic species. The lakes in the province that had been invaded by C. sowerbii up until 2014 were mapped, and data concerning their maximum depth, area, perimeter, altitude, water transparency, and the concentrations of chlorophyll a, dissolved organic carbon (DOC) and total phosphorus in the water, were compiled and analyzed. Over the study period, C. sowerbii was detected in 88 lakes across Québec; these were mainly located in the Laurentides, Outaouais and Estrie regions, where lakes are particularly abundant. The statistical analyses used showed that blooms of the freshwater jellyfish in Québec were most frequently observed in lakes with a surface area greater than 2.8 km2 and a concentration of total phosphorus in the water of less than 14.77 μg/l.