Trader consensus on Polymarket favors a Chicago high of 64-65°F at 29.5% implied probability, aligning with the latest National Weather Service and NOAA model ensembles showing ensemble means around 64°F for March 26 amid a cool upper-level trough over the Midwest. Recent GFS and European model runs from the past 24 hours indicate mild recovery from earlier cold snaps, with light southerly winds and partial sun boosting daytime heating, though persistent cloud cover and lake-effect moderation cap extremes. High uncertainty stems from volatile spring patterns—key variables include timing of any shortwave disturbances, boundary layer mixing, and urban heat island effects in Chicago—which could swing outcomes 5-10°F, as reflected in the fragmented probabilities across 60-71°F bins. New 12Z model updates expected today may refine steering patterns and refine trader positioning before resolution based on official O'Hare observations.