Recent National Weather Service and model guidance for Chicago on August 22 highlight uncertainty in overnight radiative cooling under variable cloud cover and light winds, keeping the market-implied odds for the lowest temperature tightly clustered near the long-term average low of 64–66°F. Lake Michigan moderation and potential scattered showers or a weak frontal boundary could either suppress or enhance minimum readings, with ensemble spreads showing some solutions dipping below 60°F while others hold above 70°F. Traders weigh these factors against historical August variability, where clear, calm nights produce sharper drops and any increased humidity or marine influence limits cooling. Updated model runs and evening observations tomorrow will likely refine the outcome before resolution.