Forecast models from Environment Canada and others indicate clear skies over Toronto on August 21, favoring strong nocturnal radiative cooling that typically produces overnight lows near 16°C. This aligns with late-summer climatology, where the average minimum hovers around 15–16°C under similar high-pressure conditions. Traders assign nearly equal weight to 13–15°C outcomes because small variations in wind speed, boundary-layer mixing, or urban heat-island retention can shift the recorded minimum by 1–2°C. Persistent clear conditions and light winds support the clustered probabilities, while any unexpected increase in cloud cover or advection of warmer air would push the low higher. Updated model runs tonight will refine the exact threshold before resolution.