The Old World climbing fern, Lygodium microphyllum, is an invasive weed in the Florida Everglades and the leaf roll galling mite, Floracarus perrepae, is a proposed biological control agent. Field studies were conducted for one to two years at sites in its native range in Australia, New Caledonia, and India to evaluate the effect of climate on F. perrepae. Monthly counts of the proportion of L. microphyllum subpinnae (leaflets) with leaf roll galls were used to measure the incidence of damage caused by F. perrepae. Between sites the most significant weather variable was rainfall 14 to 28 days prior to sampling, with higher levels having a depressive effect on the incidence of leaf rolls. Within sites the mean maximum temperature was the only significant weather variable, showing a decrease in the incidence of leaf rolls above 27°C, and it was predicted that no leaf rolls would form above 35°C. The weather parameters in Homestead, Florida for 2002 were within the range of those evaluated in the eight native range field sites. Thus, we do not predict that climate will prevent the establishment of this biological control agent for L. microphyllum in southern Florida.