Blisters at the root of the genitals in hot weather may be caused by eczema, genital herpes, trauma and other reasons. 1. Eczema: hot weather sweat secretion, do not pay attention to the genital cleanliness as well as hygiene, will induce eczema, which will lead to genital root blisters. 2. Genital herpes: genital herpes is triggered by herpes simplex virus infection, which can invade the genital mucosa, and will be manifested in the clinic as small blisters appearing around the genital organs, and some people will also be accompanied by a burning sensation, vesiculation, and itching symptoms. 3. Trauma: If the skin at the root of the genitals is burned or contused, causing damage to the skin and mucous membrane, it can also lead to blisters at the root of the genitals. After the blisters appeared at the root of the genitals, you need to go to the hospital in time for examination, according to the cause of the symptomatic treatment.