A headache when it is hot may be related to cerebral vasodilatation, insufficient cerebral vascular perfusion and other reasons. 1. Vasodilatation: High temperature can lead to accelerated blood circulation throughout the body, blood vessel congestion in the brain, and increased intracranial pressure, which can lead to headache. 2. insufficient cerebrovascular perfusion: people in the high temperature environment, there can be vasodilatation or a lot of sweating, which can lead to a reduction in the return of blood to the heart, there can be insufficient cerebral perfusion, which can lead to the symptoms of headache. It is recommended that people who suffer from headaches when they are hot pay attention to the timely dissipation of heat, and if there are other symptoms of discomfort, it is necessary to consult a doctor in a timely manner to clarify the cause of the disease and standardize the treatment under the guidance of the doctor, so as not to delay the condition of the body to bring about adverse effects.