Persistent northeast monsoon flow combined with a high-altitude anticyclone is maintaining stable, dry conditions over southern China, keeping Hong Kong’s overnight minima near 27°C according to Hong Kong Observatory guidance. Model consensus shows light easterly winds moderating on September 19, limiting radiational cooling and preventing significant drops below seasonal norms for mid-September. Recent observations confirm daytime maxima of 31–33°C with low humidity, consistent with the current fine-weather regime and the absence of frontal passages or heavy rain that could briefly lower temperatures. Traders appear focused on the narrow range around 27°C as the most probable minimum, while assigning limited weight to cooler or warmer outliers given the short forecast horizon and stable steering pattern.