**Current forecasts from Environment Canada and supporting models project an overnight minimum near 10°C for Toronto on September 20 under partly cloudy skies and light northerly winds shifting from earlier easterly flow.** This setup favors cooler surface temperatures as drier air advects in, consistent with the observed cooling trend through mid-September where recent nights have dipped to 11–12°C. Historical normals place the average low at 12.9°C, so the current guidance sits slightly below baseline and aligns with trader emphasis on the 8–13°C range, though model spread and timing of any clearing introduce uncertainty that sustains the 18°C+ outcome at 49% implied probability. Official minimum readings later tonight will resolve the market, with any revisions to wind or cloud cover in updated guidance the key near-term driver.