Recent model runs show a cold air mass advancing southward into the Sichuan Basin around September 27, introducing northeasterly flow, increased cloud cover, and scattered light rain that should suppress daytime heating and promote nocturnal radiative cooling. Local Chengdu Meteorological Office guidance points to a minimum near 19°C under these conditions, while some global ensembles maintain warmer boundary-layer temperatures near 22–23°C if the front stalls or weakens. High humidity (75–85%) and light winds further modulate the diurnal range, keeping the overnight low sensitive to exact precipitation timing and cloud persistence. With official forecasts diverging on frontal timing, trader-implied probabilities remain nearly even between sub-19°C and 28°C+ outcomes. Updated NMC guidance and next model cycles will clarify the low-temperature threshold before resolution.