A low-pressure trough and potential system developing near Hainan, expected to track across the northern South China Sea near Hong Kong around September 1, is the main driver behind the closely matched market odds for a 30–31°C daily maximum. Official Hong Kong Observatory guidance forecasts a range of 27–31°C under mainly cloudy skies with scattered showers and thunderstorms, while private models diverge on cloud cover, rainfall timing, and northerly wind strength that could limit surface heating. These factors create genuine uncertainty in peak temperature, consistent with historical early-September averages near 30–31°C and the absence of strong subsidence or clear skies that would push readings higher. Updated model runs and HKO briefings over the next 24 hours will likely refine the outcome.