Current forecasts from NOAA and private models indicate a warm overnight low for Chicago on August 30 driven by southerly flow advecting moist air and persistent cloud cover that limits radiational cooling. This setup supports market-implied odds clustering around 70–73°F, as stronger winds or clearing skies could drop readings toward 66–69°F while thicker clouds or showers hold minima near 74–77°F. Model consensus shows limited spread in 850 hPa temperatures but notable uncertainty in boundary-layer moisture and timing of any prefrontal convection, which traders weigh against historical August climatology where clear nights allow faster drops. Updated NWS guidance and mesoscale runs over the next 48 hours will likely refine these probabilities.