Forecast models from sources including GFS runs and regional services indicate a high near 29°C in Shanghai on September 12 under northeast winds of 8–13 km/h, partly cloudy to clear skies, and minimal precipitation risk. This setup supports moderate daytime heating with dew points in the mid-teens Celsius and relative humidity dropping below 60% during peak hours, consistent with early-autumn conditions slightly above the long-term September maximum average of 27°C. Current observations on September 11 show stable high pressure near 1020 hPa with light northeasterly flow, limiting cloud buildup and favoring the market-implied clustering around 28–29°C. Minor model spread on exact cloud timing keeps 30°C a lower-probability outcome while rendering extremes below 27°C or above 31°C unlikely absent rapid changes in steering patterns. Updated model guidance overnight will refine the final peak.