Recent Environment Canada forecasts for Toronto Pearson International Airport peg the May 16 high near 23°C under partly cloudy skies, yet a 40–60% chance of afternoon showers introduces the key uncertainty driving the tight market clustering around 22–24°C. Variable cloud cover limits solar insolation and surface heating, while southwest winds may enhance boundary-layer mixing and briefly boost peaks before any precipitation arrives. Mid-May climatological averages near 19–20°C provide baseline context, but the current warming trend from cooler prior days leaves room for 1–2°C variance depending on shower timing and clearing. GEM and GFS ensemble runs show strong consensus within this narrow band, with afternoon hourly observations at the resolution station poised to settle outcomes among these closely matched probabilities.