A prediction of forest insect defoliator climatic release hypotheses is that there will be a consistent association between outbreaks and weather favorable to fitness. However, such predictions are difficult to test. Simplifying assumptions regarding population processes, definition and delineation of outbreaks, and the nature of climatic variation are usually required. To determine if there was a relationship between saddled prominent,Heterocampa guttivitta(Walker), outbreaks and moisture condition, we grouped infestations into outbreaks based on correlation of drought between climatic regions and overall spatial and temporal pattern of infestations. We then developed parametric tests using these outbreaks as independent observations. No consistent relationship between drought as indicated by the Palmer hydrological drought severity index and outbreaks was found. Implications of our procedure are discussed in terms of other studies involving climatic release hypotheses.