Efficiency of cooling tower is high in winter or summer?

The bigger the temperature difference between the internal heat source and the external environment where the surplus heat is dumped, the more efficient is the process in achieving mechanical work – in this case, turning a generator[1]. Hence the desirability of having a high temperature internally and a low temperature in the external environment. This consideration gives rise to desirably siting power plants alongside very cold water.*

Many power plants, fossil and nuclear, have higher net output in winter than summer due to differences in cooling water temperature.

the efficiency of a cooling tower depend mainly on the cooling area ,the highiet of the tower , the fluid of  cooling(that heat trnsfer) the fluid to bee cooled ..the winter may affect the efficiency but can be neglected.

high efficiency in summerbecause the cooling tower depend mainly on the vaporization of some droplet of water.

If you introduce the efficiency as approaching the temprature diffrence base on water vaporization, in winter cooling tower would be more efficient, because with less water vaporization you can approach the temprature diffrence and also your concentration constant and make up would be decrease.

one word winter