A lot of small rice-like lesions on the face in summer may be caused by solar dermatitis, freckles, prickly heat and other diseases. 1. Solar dermatitis: Solar dermatitis is caused by the skin receiving more than the tolerated amount of ultraviolet radiation. Since ultraviolet rays are relatively strong in summer, if the face is exposed to ultraviolet rays for a long period of time, skin erythema and blisters may appear, which may be manifested as many small rice grain-like lesions. 2. Freckles: Freckles may be caused by heredity, light and other factors. Freckles occur in the face, and the lesions are round, oval, irregular, and the size of a needle tip to a grain of rice, which can appear symmetrically, and can be aggravated in summer after sun exposure, and the patients can show a lot of small rice grain-like lesions. 3. Prickly heat: Prickly heat is caused by high ambient temperature, prolonged bed rest, and humid environment. The patient’s skin manifestation can be small blisters, often appear in batches, the patient will appear small rice-like lesions. If the patient has a lot of small rice-like lesions on his face in summer, he should go to a regular hospital to find out the cause of the disease.