The market's near-certain positioning on a 76-77°F high for Denver on September 21 reflects the National Weather Service's official climatological observations confirming a maximum temperature in that narrow range at the primary reporting station. Preceding conditions featured partly cloudy skies with light winds and no significant moisture, aligning closely with seasonal normals around 77°F while falling short of late-summer heat records. Model consensus from NOAA guidance had projected similar values days ahead, limiting volatility. Scenarios that could have shifted outcomes, such as stronger downslope warming or unexpected cloud cover altering the diurnal range, did not materialize, allowing trader capital to converge rapidly on the verified data ahead of final resolution.