**Trader sentiment for Chicago’s lowest temperature on September 16 centers on a mid-60s outcome, with the 66-67°F bin holding the highest implied probability at 34.5%.** This distribution reflects broad agreement among short-range forecast guidance that the daily minimum will occur overnight under mostly cloudy skies and northeast winds. Current National Weather Service and ensemble model runs project an overnight low near 64–67°F, driven by persistent cloud cover that limits radiational cooling, moderate northeast flow off Lake Michigan, and scattered showers that maintain higher dew points. These conditions contrast with clearer, calmer nights that would allow temperatures to drop into the upper 50s. Recent days have featured a cooling trend after mid-September warmth, but the pattern has stabilized around seasonal normals rather than producing sharp drops. Key variables that could shift the outcome include any unexpected clearing after midnight (favoring the 62–65°F range) or stronger onshore flow and additional rainfall (pushing the minimum toward 68–69°F). With resolution less than 24 hours away and limited model spread, traders have concentrated probability in the narrow 64–69°F window while assigning low odds to extremes below 60°F or above 72°F. Updated NWS forecast discussions and hourly observations overnight will provide the final inputs before the market settles.