**Dominant trader consensus on sub-275 mm total precipitation for Hong Kong in September 2026 rests on verified low rainfall accumulation through September 24 and dry conditions forecast for the final days.** Official Hong Kong Observatory data show just 94.2 mm recorded at the Observatory site by September 24—well below the 1991-2020 climatological normal of roughly 321 mm—with only trace or zero amounts on most days and the largest single-day total at 37.9 mm. High-pressure dominance and a northeast monsoon have suppressed convective activity, keeping relative humidity moderate and cloud cover limited during peak periods. The remaining window (September 25–30) features high-pressure ridging, mostly sunny skies, and low precipitation probabilities according to Hong Kong Observatory outlooks, with any distant tropical cyclone activity (such as Shuliki) steered away from the region. This combination makes totals approaching or exceeding 275 mm highly improbable absent a late, intense, and unexpected rain event. The market-implied 98.3% probability on <275 mm reflects traders’ assessment of these confirmed observations and short-term model consensus, while acknowledging residual uncertainty from rapid changes in steering patterns or unforecasted convective bursts in the final 48–72 hours.