Recent National Weather Service point forecasts and ensemble guidance for Chicago O'Hare indicate the overnight low on October 6 will likely occur between 49–57 °F under clear skies and southwesterly flow of 5–15 mph, with radiative cooling dominating after sunset. The spread in market-implied probabilities across the 40–57 °F bins reflects lingering uncertainty in boundary-layer mixing and exact timing of the minimum, as well as Chicago’s urban heat-island and Lake Michigan moderation effects that can shift readings by several degrees. Traders are weighting the latest model runs and climatological analogs showing mild early-October nights, while watching for any final forecast adjustments before resolution.