Aestivation (also spelled estivation) is a state of dormancy that occurs in some animals during periods of high heat or drought. It serves as a survival strategy that reduces metabolic activity and conserves energy when environmental conditions become too hot or too dry for normal functioning. The duration of aestivation can vary widely depending on climate and species, ranging from a few days to several months.

Aestivation is considered an ecological and evolutionary adaptation that allows organisms to survive seasonally harsh environments. It is broadly comparable to hibernation, which occurs during cold conditions, although the triggers and physiological mechanisms differ.