**Near-even market odds between sub-7°C and 16°C+ lows on October 2 reflect substantial uncertainty in overnight radiational cooling after a frontal passage.** Environment Canada forecasts a daytime high near 20°C with clearing skies Friday night, supporting a minimum around 9°C under light winds and moderate dew points, consistent with seasonal norms of roughly 10–11°C. Ensemble models diverge on boundary-layer mixing and the strength of any post-frontal high, with some runs allowing deeper cooling toward 6–7°C while others retain warmer advection or residual cloud cover that limits temperature drops. Traders are pricing the balance between these scenarios, with resolution hinging on the final observed minimum from official Toronto stations. Updated 00Z and 12Z model cycles plus Environment Canada’s next guidance release will likely shift implied probabilities.