Recent National Weather Service forecasts for Chicago show an overnight low in the mid-50s Fahrenheit on October 15, driven by a warm air mass advected by easterly to northeasterly flow ahead of an approaching cold front. Model consensus from recent runs supports temperatures remaining well above seasonal normals (historical mid-October lows near 46°F), with minimal overnight radiational cooling due to persistent cloud cover and rain. This setup explains the market-implied emphasis on outcomes above 50°F, while the modest probability assigned to 49°F or below reflects limited downside risk from forecast shifts. Traders are weighting the latest model guidance and observed warmth through mid-October against typical variability in steering patterns and precipitation timing that could alter the minimum by a few degrees.