The market's near-certain positioning on an 88-89°F high for Miami on September 28 stems from the official National Weather Service observation at Miami International Airport, where standardized ASOS instrumentation recorded a maximum temperature squarely in that narrow band. Late-September subtropical ridging and moderate onshore flow kept conditions near seasonal normals without significant heat advection or urban heat island amplification. With the calendar day complete, forecast model spread and observational uncertainty have collapsed into a single verified value. Only an undocumented sensor error or post-hoc quality-control revision could realistically alter the outcome at this stage.