**Trader consensus centers on a minimum of 27°C (57.5% implied probability) or 28°C (26.5%) for September 22 in Hong Kong, with 26°C a distant third at 12.5%.** These odds reflect the latest official forecasts showing the northeast monsoon beginning to influence the South China coast, combined with upper-air disturbances that will bring mainly cloudy conditions and isolated showers. The Hong Kong Observatory’s 9-day forecast explicitly lists a 27–32°C temperature range for Tuesday, September 22, under light east-to-northeast winds of force 2–4. Multiple global and regional models align closely, projecting overnight lows in the 26–27°C range during pre-dawn hours before gradual daytime warming to 29–32°C. This places the daily minimum near the lower end of the forecast envelope, consistent with the market’s heavy weighting toward 27°C. Key drivers include the timing of monsoon onset—still in its early stage on the 22nd—so significant cooling has not yet materialized, and persistent high humidity (65–95%) that limits radiative cooling overnight. Historical September baselines for the Observatory station average overnight minima near 25–26°C, but current steering patterns and the absence of stronger northerly flow keep readings slightly elevated. Model consensus remains tight, with limited spread in guidance, supporting the narrow probability distribution around 27–28°C. Any late forecast revision from the Observatory or updated model runs ahead of resolution could shift these odds.