This market will resolve to the temperature range that contains the highest temperature recorded by NOAA at the Chicago O'Hare Intl Airport Station in degrees Fahrenheit on 3 Sep '26. The resolution source for this market will be information from NOAA, specifically the highest reading under the "Temp" column for all times on this day, available here: https://www.weather.gov/wrh/timeseries?site=kord This market will resolve off of the Hourly Data provided using the "Show Hourly Data" button. If NOAA data for the observation date is unavailable by 11:59 PM ET on the day following the observation date, the Weather Underground Daily Observations table will be used as the resolution source. In the event that there is no data for the observation date by 11:59 PM ET on the day following the observation date, this market will resolve to the lowest bracket. To toggle between Fahrenheit and Celsius, click the "Switch to US Units w/ kts" button until the relevant table displays °F. This market will resolve once the first data point for the following date has been published on the resolution source, or by 11:59 PM ET on the day following the observation date, whichever comes first. The resolution source for this market measures temperatures to whole degrees Fahrenheit (eg, 21°F). Thus, this is the level of precision that will be used when resolving the market. Revisions to temperatures recorded within this market's timeframe will be considered until the first datapoint for the following date has been published, after which any alterations will not be considered.
Traders assign 100% implied probability to a 90-91°F high in Chicago on September 3 because official National Weather Service station data from the day confirm a verified daily maximum squarely in that range. Surface observations, combined with stable high-pressure ridging and light winds, produced peak temperatures consistent with both short-range model guidance and early-September climatology for the Midwest. The market resolution depends on post-event quality-controlled measurements rather than forecasts, leaving little room for revision. Only an unusually large data adjustment—highly uncommon at primary reporting sites—could alter the outcome, and no such discrepancies have emerged in initial reports.