Heat stress (HS) caused by above-optimal temperatures adversely affects plants’ growth and development and diminishes crop yields. In natural and agricultural environments, these stresses are often... Show moreHeat stress (HS) caused by above-optimal temperatures adversely affects plants’ growth and development and diminishes crop yields. In natural and agricultural environments, these stresses are often transient but recurrent and may progressively increase in severity over time. In addition to the inherent ability to cope with a single HS event, plants have evolved mechanisms that enhance their capacity to survive and reproduce under such conditions. This involves the establishment of a molecular ‘thermomemory’ after moderate HS that allows them to withstand a later — and possibly more extreme — HS event. Here, I summarize the current understanding of the molecular and biochemical mechanisms underlying thermomemory across multiple cellular levels and discuss aspects that require further attention. Show less