-While summer, you can store the whole watermelon at room temperature, and it will be safe for up to two weeks. -Store the sliced melon in an airtight container in the fridge, and it will be safe for up to 4-5 days. -To store a half melon, wrap it in plastic wrap and fridge it. It will be safe for 4-5 days. -You can also put the sliced watermelon pieces on wax paper and then freeze them. After they are completely frozen, transfer them into an airtight container. Then freeze them. They will be safe for up to three to six months. -Never preserve them with tomatoes or apples. That will damage the melon and reduce its longevity.