Certified GKH Gardening Expert
This is not the best good time to plant apples. The heat combined with overwatering in an attempt to compensate for heat will usually disable a tree quickly. These should be planted in very early autumn, or better, spring. This will avoid any heat or cold damage and allow the roots time to develop and take hold before any hot or cold weather arrives.
This article will help you to plant apple trees: https://www.gardeningknowhow.com/edible/fruits/apples/apple-tree-planting.htm