**Recent atmospheric conditions and forecast model spreads are driving the closely matched probabilities around 20–26°C for Guangzhou’s September 6 overnight low.** Persistent northwest winds, high humidity near 70–80%, and widespread cloud cover or scattered thunderstorms expected through the weekend are limiting daytime heating while moderating radiative cooling at night, keeping projected lows clustered near 24–26°C. These align with September climatology of roughly 24–25°C but reflect uncertainty from variable precipitation timing and model differences in boundary-layer moisture. Traders appear to weigh the chance of clearer skies or stronger cooling under lighter winds against the more likely stable, humid pattern, producing a tight distribution across the 20°C-or-below through 26°C outcomes. New model runs and official China Meteorological Administration guidance over the next 48 hours will likely refine these market-implied odds.