I validate our blood/blood product shipping containers, both AABB approved boxes and coolers twice a year. I validate them at room temperature and then also perform an extreme validation. During the summer, I don't have a problem finding a warm day. This past winter, when I was doing the extreme validations, we had some unusually warm temps those days. My QA dept. questioned my outside temp of 52F for a winter validation; claiming this was not an extreme validation. I am wondering if anyone else does an extreme validation during the winter and the summer and do you have specific temp ranges that your extreme validations must be performed in. Lisa