Sweating on the forehead when it is hot is considered a normal sweating reaction, but it may also appear as a reaction to hyperhidrosis. The forehead contains a large number of sweat glands and is a dense area of sweat gland distribution. Once sweating occurs, some people have severe sweating in the forehead, while others may have severe sweating in the back, chest or top of the head. Each person’s sweat gland distribution area is somewhat different, and this difference is reflected in the severity of sweating. Therefore, if the sweating is more pronounced on the forehead, it is usually due to the dense distribution of sweat gland tissue in the forehead area.