The overwhelming market consensus on 29°C as Shanghai’s peak temperature on September 13 reflects real-time observations from official monitoring stations under mostly clear skies with light northeasterly winds. This outcome aligns with mid-September climatology in the Yangtze River delta, where subtropical high pressure typically caps daytime maxima near seasonal averages without strong frontal influences or typhoon activity. Ensemble forecasts from global models showed tight clustering around 29°C through the afternoon, with low spread supporting the near-certain implied probability. Only a late revision in verified station readings or an unexpected localized heat spike could alter resolution, though current data indicate stable conditions.