Official observations from Chicago's O'Hare International Airport, the National Weather Service's primary measurement site, recorded a high temperature of 66°F on March 26 amid mild spring conditions with partly cloudy skies, light southerly winds around 10 mph, and no significant weather disruptions. This aligns with NOAA climatological data showing mid-March averages near 50°F but recent warm anomalies pushing into the mid-60s, supported by upper-air patterns favoring southerly flow. Trader consensus at 100% implied probability reflects this confirmed reading, with skin-in-the-game bets aggregating real-time station data. Realistic challenges are minimal—only rare post-audit revisions from auxiliary sensors or data quality issues could shift it, pending final NWS daily summary.