Winterization refers to the process of preparing something for an upcoming winter.
The term is most commonly used in respect to aquatic play features, fountains, and the like, which must be drained and sealed up so that water inside does not freeze, causing breakage of the pipes in the fountain, or the like.
In the New England area, many wealthy families living in cities during the 19th century had summer homes in the mountains. This was to flee the onset of yellow fever and other epidemics which often struck in the summer months, when city plumbing problems and stagnant horse manure in the streets caused a health hazard. Winterization would take place each Fall when the families returned to the cities (often when school started). In those days, winterization just referred to a lock-down of all movable parts as protection from winter storms. An example of such a summer home that needs to be winterized each fall is the scene of the movie On Golden Pond, which was filmed on Squam Lake.
In the 20th century, these summer mountain homes in turn, were winterized to enable winter holidays, as the popularity of skiing in the mountains increased over the popularity of summer camping. In this sense, winterization refers to the addition of modern amenties such as heating and insulation, often entailing a complete rebuild of the cottage. An example of a former New England summer colony that has been transformed into winter cabins is Killington, Vermont.