**Northeast monsoon dominance and limited tropical moisture are positioning September 2026 rainfall totals well below the long-term average of roughly 288–321 mm.** As of September 10, early-month accumulations stand near 50 mm, with Hong Kong Observatory data and short-range forecasts indicating mostly dry to partly cloudy conditions under easterly to northeasterly flow. A broad low-pressure area expected to form in the South China Sea later in the week may bring scattered showers and thunderstorms over the weekend, yet model consensus points to only modest additional rainfall rather than prolonged heavy events. With roughly two-thirds of the month remaining and no strong signals for an active monsoon trough or typhoon landfall, trader-implied probabilities heavily favor totals under 275 mm. Upcoming 9-day forecasts and any revised tropical cyclone guidance will be the key near-term catalysts that could shift these odds.