Official forecasts from the National Weather Service indicate the daily minimum in Chicago on October 15 will occur overnight as a cold front and northwest winds advect cooler, drier air behind widespread showers, with gusts to 30 mph enhancing mixing and surface cooling. Current early-morning readings near 58–60 °F under overcast skies and southeast flow are expected to fall steadily after midnight, with model guidance converging on a low in the low-to-mid 50s °F at O’Hare and Midway. Trader consensus reflected in the near-even odds between the 56–59 °F and 52–53 °F bins captures remaining uncertainty in exact wind timing, residual cloud cover, and urban heat-island effects. The market will resolve on the official 24-hour minimum reported by the National Weather Service station.