Traders see the highest temperature in Chengdu on August 16 clustering around 31–33°C because ensemble forecasts from global and regional models show modest day-to-day variability in the Sichuan Basin’s humid subtropical regime. High humidity, limited diurnal mixing, and frequent afternoon convection tied to the East Asian monsoon keep maximums from spiking sharply, while the basin’s topography can trap heat on clearer days. Historical August averages near 31°C, with occasional 34–35°C readings when subsidence strengthens, align with the market’s spread. Small shifts in cloud cover, precipitation timing, or updated model runs from the China Meteorological Administration will likely decide whether the peak settles at 31°C, 32°C, or 33°C, reflecting genuine short-range forecast uncertainty rather than a single dominant driver.