Hong Kong Observatory forecasts for September 21 point to a maximum of 27–31°C under mainly cloudy skies with a few showers and isolated thunderstorms, as a weakening anticyclone gives way to increased moisture and reduced solar heating. This setup, with relative humidity expected near 70–95%, supports trader emphasis on 31°C and 32°C outcomes by limiting afternoon temperature spikes compared to clearer prior days. Model consensus shows modest variability in peak readings tied to exact shower timing and wind shifts, while climatological September averages near 30–31°C provide baseline context. Updated official guidance and refined model runs over the next 48 hours will clarify whether cloud cover or brief sunny intervals push readings toward the upper or lower end of the narrow 30–32°C cluster.