Sweating in the forehead and cold skin in summer may be caused by physiological factors, hyperthyroidism and other pathological factors. 1. Physiological factors: in the summer when the weather is hot, the body will regulate the body temperature through sweating, due to the evaporation of sweat will take away part of the heat, so the patient may feel cold skin. Due to the lack of air permeability of the clothes, or the presence of some patients with more developed sweat glands in the chest, may lead to sweating in the chest. This is a normal physiological phenomenon, no need to worry too much. 2. Pathological factors: when the patient has underlying diseases, such as hyperthyroidism, etc., due to the increase in the basal metabolic rate, the patient may experience excessive sweating. These are only some of the common causes. If the patient is out of the hot environment, change the cooler clothing, there is still sweat in the chest and cold skin, it is recommended to consult a doctor to clarify the diagnosis, and follow the doctor’s instructions to standardize the treatment.