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I can't give you any information about costs, but it does freeze in the winter, and houses generally have no insulation. In fact, many have blocks with holes in them set in the walls, guaranteeing some time huddling around space heaters. New apartment buildings might be quite different, however. Even when it is cold during the night, it generally will warm up during the day. Coming from Jamaica, the first year wills seem a lot colder than the second.