**Persistent high-pressure systems and northeast monsoon influences have suppressed rainfall across Hong Kong through mid-September 2026, driving the strong market consensus toward totals below 275 mm.** Official Hong Kong Observatory data show only 94.2 mm accumulated through September 17—well below the 1991–2020 climatological normal of 321.4 mm for the full month. The first half of September featured mostly dry or trace-rain days after early-month showers, with mean relative humidity around 75% and limited cloud cover under subtropical ridge conditions. Recent 9-day forecasts from the Observatory and model guidance indicate continued generally fine to partly cloudy weather for late September, with only low-to-moderate chances of isolated showers or thunderstorms and no imminent tropical cyclone threats. These drier steering patterns and atmospheric stability sharply reduce the likelihood of the heavy, prolonged rain episodes typical of September climatology. With roughly 13 days remaining and current conditions favoring light or negligible additional accumulation, the implied probability heavily favors a below-normal seasonal total. Updated model runs or any late-month monsoon break could still introduce modest upside risk, but the dominant signal supports the current market positioning.