We excrete more urine during winter than during summer due to

During summer, we lose water in the form of sweat. Hence the kidneys retain water for maintaining the fluidity of the blood and less urine is formed. During winter, there won’t be any sweating due to low temperature and hence no evaporation losses. Moreover, the blood capillaries in the skin get constricted and the blood pressure is increased. In order to maintain the normal blood pressure, the excess water along with the wastes is excreted mostly in the form of urine.