Official measurements from National Weather Service stations, including Chicago O'Hare, recorded a daily maximum of 74–75°F on September 13, 2026, under partly cloudy skies with a moderating northerly flow and dew points in the 50s that limited afternoon heating. This aligned with the National Weather Service forecast discussion emphasizing mid-70s highs due to a post-frontal air mass and minimal insolation from scattered clouds. Trader consensus at 100% implied probability for the 74–75°F bin reflects confirmed observational data rather than models. Resolution could face minor challenge only from rare station-specific discrepancies or quality-control revisions, though such adjustments remain improbable given consistent regional reports.