The unusually hot summer temperatures that we have been experiencing on the West
Coast is stressing our fruit trees. I have seen sunburn on leaves and fruit similar to the type of damage that is common in the hot dry areas of the interior. When temperatures rise to 35+ degrees C this type of damage happens quickly to exposed fruit and older leaves.
Of more concern for apples is the development of Bitter Pit. This is a temporary Calcium deficiency induced my drought. The BC Ministry of Agriculture has an excellent information page about this
problem: Bitter Pit. The way to avoid this problem is to provide your trees with consistent adequate soil moisture. The damage is usually concentrated on the calyx end of the fruit and it will be worse in very large fruit and on young fast growing trees. Excess pruning and applications of too much nitrogen will aggravate this problem.
If you have one of these problems and willing to share please send me some images.