Persistent northeast winds and extensive cloud cover from recent heavy rainfall are moderating overnight temperatures across the Chicago area, with National Weather Service guidance pointing to a Tuesday minimum in the mid-50s. Official point forecasts show lows near 55–56°F under mostly cloudy skies and continued onshore flow off Lake Michigan, limiting radiational cooling. Ensemble model spreads create tight market clustering around 54–57°F bins, reflecting uncertainty in exact wind speeds and any late clearing that could allow slightly lower readings. Historical September averages near 56°F provide baseline context, while the short two-day horizon to resolution means traders are closely watching updated NWS runs and local observations for any shifts in the thermal profile.