Northwest winds behind a recent frontal passage are advecting cooler, drier air into the Chicago area, while mostly clear skies overnight will enhance radiational cooling. National Weather Service and model guidance indicate the minimum temperature on August 23 will likely fall in the upper 50s to low 60s, with several forecasts centering near 60–62°F—well below the late-August climatological average low of about 66°F. Light winds and low dew points further support efficient surface cooling, though any increase in cloud cover or wind could limit the drop. Trader consensus reflected in the market odds aligns closely with this guidance, assigning the highest probabilities to the 58–61°F bins as the dominant near-term outcome.