Climate change is increasing the frequency, intensity, and duration of extreme weather events, including Marine Heat Waves (MHWs). MHWs pose a significant threat to marine ecosystems and marine organisms, including oysters, oyster reefs and farmed oysters. We investigated the survival and growth of juveniles of two commercial species of oyster, the Sydney rock oyster, Saccostrea glomerata, and the Pacific oyster, Crassostrea gigas, to a moderate and an extreme MHW in context with recent MHWs and beyond. The survival and size of Pacific oysters to moderate MHWs (22 – 32 °C; 14 days) was greater than that for Sydney rock oysters (24 – 32 °C; 15 days). While survival and growth of both species was significantly impacted by extreme MHWs (29-38 °C; 5-6 days), Sydney rock oysters were found to survive greater temperatures compared to the Pacific oyster. Overall, this study found that Pacific oyster juveniles were more tolerant of a moderate MHW, while Sydney rock oyster juveniles were more resilient to extreme MHWs. These differences in MHW coping strategies may have consequences for aquaculture and coexistence of both species in their intertidal and latitudinal distributions and oyster reef restoration in estuaries along the south-eastern Australian coastline.