Current National Weather Service and ensemble forecasts indicate a Tuesday night low for Chicago around 56–63 °F under partly to mostly cloudy skies, with southerly flow advecting milder air and a 40 % chance of showers after midnight that could limit radiational cooling. Lake Michigan’s moderating influence, combined with urban heat retention and variable cloud cover, narrows the likely diurnal minimum while model spread in boundary-layer moisture and wind speed creates the observed near-even market split between sub-45 °F and 64 °F-plus outcomes. Updated model runs and the 48-hour forecast horizon remain the key variables that could shift the final overnight minimum before resolution.