Most homeowners notice they need a window cleaning when the streaks and smudges become hard to ignore — but by then, the buildup has usually been there for months. In Montreal and Laval, seasonal changes mean pollen in spring, humidity in summer, and salt and grime in winter all accumulate on your glass. A seasonal clean — or at minimum once or twice a year — keeps your home looking well-maintained and lets more natural light in year-round.