If you have small blisters on your hands in hot weather, there are several factors: 1. From the perspective of Chinese medicine, this is a summer dampness type of infection, when the weather is too hot heat and dampness into the inside, there will be small blisters on the body and hands. 2. From the perspective of Western medicine, the most common factor is the infectious factor, if the body is infected with bacteria, viruses, fungi and other microorganisms at this time, especially the hands are particularly susceptible to infection. The most common factor from the western medical point of view is the infectious factor.