Happiness is affected by many factors, and there is no definitive scientific explanation about whether the weather is directly related to good mood.
But what is certain is that the four seasons do affect the mood.
There is a symptom called “seasonal depression”, which causes depression in some seasons; most patients develop symptoms in the winter, but some people will have it in the summer.
The cause of seasonal depression is unknown. Some people think that this is related to the mechanism by which the brain regulates hormone secretion.
As the summer sunshine time gets longer, the concentration of hormones in the brain changes.