**Current forecasts from the National Weather Service and major models indicate an overnight low in Chicago on August 23, 2026, most likely in the low-to-mid 60s°F under mostly clear skies and light northerly to northwesterly winds.** This setup promotes strong radiative cooling after daytime highs reach the mid-70s, with traders assigning the highest implied probabilities (75% combined) to the 58–61°F bins. Key scientific factors include the arrival of cooler, drier air behind Saturday’s weak frontal passage, reduced cloud cover allowing efficient heat loss from the surface, and typical late-August boundary-layer dynamics near Lake Michigan that can moderate extremes. Model spreads arise mainly from small differences in predicted wind speeds (which affect mixing) and any residual moisture, which explains the tight clustering around 58–63°F rather than a single dominant outcome. Historical August 23 lows average near 66°F, so this represents a modestly below-normal night driven by the current synoptic pattern. Upcoming NWS forecast updates and evening model runs will provide the final data points before the minimum is recorded.