Observed high temperatures at Chicago's Midway International Airport station reached a peak of 68-69°F on June 14, locking in market-implied odds at 100% for that range. Official National Weather Service and cooperative station measurements confirm this value fell below seasonal normals near 80°F, driven by persistent cloud cover, northeasterly flow, and a stable air mass that suppressed daytime heating. Real-time surface observations and model verification from the prior 48 hours aligned precisely with this outcome, leaving minimal scope for revision. Only a post-event station data audit or rare instrumentation discrepancy could alter resolution, though historical precedent shows such adjustments are infrequent for daily maxima.