The pattern of Odonata species-richness in Britain is mapped at 10 km resolution. This is strongly correlated with mean air temperatures. The relationship with seasonal and monthly mean temperatures is explored: summer temperatures are better predictors of overall dragonfly richness than are winter temperatures. However, there appears to be some latitude variation in the relationship. Thus, in northern Britain, increasing Odonata richness is correlated with increasing summer temperatures for non-boreal species, and with decreasing winter temperatures for predominantly-boreal species; physiological adaptations of individual species are proposed as a possible explanation.