Berries of certain cultivars of Vitis vinifera are prone to loss of mass late in ripening, which is often evident as berry shrivel that has impacts on yield and wine quality. Loss of berry mass late in ripening correlates with cell death in the mesocarp, which is exacerbated by high temperatures and water stress. These stresses result in a greater degree of hypoxia in the berry mesocarp depending on the anatomical constraints for berry gas exchange. Hypoxia is caused by increased respiration rates under high temperature and restricted oxygen diffusion into the berry. The hypoxia and resulting biochemical responses (fermentation, ethanol production and ROS production) probably trigger cell death. Cell death then alters the water relations of the berry such that water can be withdrawn from the berry to the parent vine, causing berry shrivel. Between cultivars there are large differences in response that are partly explained by oxygen diffusion constraints due to different anatomy but there are likely differences also in biochemical responses to high temperature and hypoxia. I will report on the physiological and molecular studies that have been carried out in my laboratory on Shiraz berries and other cultivars that indicate the causes of late season cell death and berry shrivel. We have aimed also to find ways of monitoring and reducing these impacts under a warming climate.