This study investigated how temperature affects the expression of seed hydration memory and the acquisition of tolerance to water deficit in Cereus jamacaru subsp. jamacaru and Xiquexique gounellei subsp. gounellei. These species, native to semiarid ecosystems, face the risk of higher temperatures due to climate change, which could exceed their optimal germination conditions and impact their survival. Seeds of C. jamacaru subsp. jamacaru were subjected to hydration and dehydration cycles (HD cycles) at 25 degrees C, 30 degrees C, and 40 degrees C, while X. gounellei subsp. gounellei seeds were subjected to HD cycles at 25 degrees C, 30 degrees C, 40 degrees C, and 50 degrees C. Both species were germinated under water deficit conditions simulated with osmotic potentials of 0.0, - 0.2, - 0.4, and - 0.6 MPa for C. jamacaru subsp. jamacaru, and 0.0, - 0.3, - 0.6, and - 0.9 MPa for X. gounellei subsp. gounellei. Germination parameters, including final germination percentage, mean germination time (MGT), and mean germination rate (MGR), were evaluated. HD cycles at 25 degrees C increased germinability and improved MGT and MGR in both species. However, at 30 degrees C, only X. gounellei subsp. gounellei showed improvements. HD cycles at 40 degrees C negatively affected both species, and at 50 degrees C, germination was inhibited in X. gounellei subsp. gounellei at - 0.6 MPa and - 0.9 MPa, indicating a loss of seed hydration memory. These findings suggest that increasing temperatures in future climate scenarios could impair the germination of C. jamacaru subsp. jamacaru and X. gounellei subsp. gounellei, reducing their tolerance to water deficit and potentially affecting their reproductive success.