Official National Weather Service observations at Chicago O’Hare recorded a maximum temperature of 81°F on September 5, 2026, reached at 2:37 PM CDT, aligning precisely with the market’s near-certain 80-81°F outcome. This reading, verified through standard climatological reporting protocols, sits just 2°F above the 1991–2020 daily normal and well below historical September extremes for the date. With the observation window closed, trader consensus reflects the final authoritative data point rather than forecasts, leaving negligible probability for alternative bins absent any post-hoc measurement revision. Cooler morning conditions and fog noted in the report further constrained afternoon warming under the prevailing air mass.