Cuenca does not have traditional seasons, which is the reason it is sometimes referred to as the Eternal Spring City. That information does not help you prepare for when to visit. We suggest you look at the Gringos Abroad article with the weather chart by clicking here.
Just for a preview, this is from another source. You can get a good idea of the average temperatures, rainfall, and daylight. Take note that indoor heating is not part of the Ecuadorian housing.