Highest temperature in Chicago on September 18? - 69 or below

Prediction market on polymarket_us. Will the highest temperature recorded at Chicago Midway Airport (KMDW) in Chicago for 2026-09-18 as reported by the National Weather Service's Climatological Report (Daily) be less than or equal to 69F? Outcome verified from NWS Climatological Report.

Resolves: 9/19/2026.