**Official observations from the National Weather Service confirm a daily maximum of 69°F at Chicago O’Hare on September 26, 2026, recorded at 12:43 PM local time.** This places the high squarely in the 68–69°F bin, aligning with the market’s near-100% implied probability. The reading came from standard automated instrumentation under clear, dry conditions with light winds, consistent with climatological expectations for late September (normal high around 72°F). With the date now passed and authoritative data released, traders face no meaningful uncertainty. The only realistic challenges would involve an improbable revision to the official record or use of an alternate station, neither of which has occurred.