Late spring and early fall. May through June and September through October are the windows where temperatures stay above 10°C consistently, asphalt shingles seal and adhere properly, and contractor scheduling is predictable.
Winter replacements are possible but they come with real risks. Asphalt shingles should not be installed below 4°C. Below that point the heat-activated adhesive strip fails to bond and the shingles get brittle during handling. Weather delays stack up. Labour time increases. If you’re booking during peak season lock your contractor in early. Demand in Windsor-Essex outpaces supply from May through September most years.
Scheduling also directly affects what you pay. The cheapest way to replace a roof includes late fall timing when contractor demand drops and quotes get competitive. Ontario’s freeze-thaw cycles also tie into how long your roof can be expected to last. A roof approaching 20 years should be assessed before another winter regardless of how it looks on the surface. For full project cost context see how much it costs to replace a 2,000 sq ft roof in Ontario.