A lot of small bumps on the neck in summer may be caused by solar dermatitis, prickly heat, filiform warts and other reasons. 1. Solar dermatitis: If the skin is exposed to a lot of ultraviolet rays in summer, it may lead to an inflammatory reaction in the neck, resulting in a lot of small bumps on the neck. 2. Prickly heat: In the summer, due to the hot weather, it may lead to the blockage of the sweat gland ducts in the neck area after a lot of sweating, which will easily cause the skin to react and appear prickly heat, that is, a lot of small bumps. 3. filiform warts: summer neck a lot of small bumps may be filiform warts caused by human papilloma virus infection caused by skin disease, has a certain degree of contagious.