Trader consensus on Polymarket overwhelmingly favors a high of 56°F or higher in Chicago on May 16 (99.4% implied probability), backed by strong alignment across National Weather Service (NWS) guidance and global forecast models like GFS and ECMWF, which project daytime highs in the mid-70s°F under a building high-pressure ridge ushering warm air advection into the Midwest. This follows a cool early May pattern, with recent 24-hour updates showing departure from lingering low-pressure influences, restoring climatological norms (average May high ~67°F at Chicago O'Hare International Airport). Model ensembles indicate low spread, with minimal support for cooler outcomes. Realistic challenges include an unexpected northward surge of a cool front or persistent low clouds capping temperatures below 56°F, though probabilities remain under 1% per current guidance; watch NWS Chicago's afternoon forecast discussion for refinements.