Blisters
A blister is a small pocket of fluid within the upper layers of the skin (between dermis and epidermis ), typically caused by forceful rubbing (friction)or burning. An irritated red skin is the first sign. The most common cause is a poor fitting shoe combined with an activity that creates excessive friction on a certain part of the foot. Generally the size and location of the blisters will determine the amount of pain.
Walking on a hot surface or walking on a hot summer day increases the temperature of the feet. This increase of temperature amplifies when pinching shoes or badly ventilated shoes are used. The higher temperature increases the risk for blistering; higher temperature demands only very little friction to weaken the different skin layers and to provoke a blister. On the other hand, cold diminishes the blood circulation which itself increases also the risk for having a blister.