Traders have overwhelmingly backed a highest temperature of 56°F or higher in Chicago on May 16, reflecting National Weather Service forecasts of a mild spring day with highs in the upper 60s to low 70s under stable high pressure. This consensus aligns with mid-May climatology for the Midwest, where average highs reach about 68°F, driven by typical southerly flow and minimal cold-air advection from the north. Recent Global Forecast System model runs show consistent daytime warming without significant cloud cover or precipitation that could suppress temperatures. An unexpected late-season Arctic front or major model bias could theoretically challenge the outcome, though such developments remain highly unlikely given current synoptic patterns and observed conditions.