Traders assign near-certainty to a 31°C maximum in Hong Kong on August 15 because official Hong Kong Observatory data recorded that precise value under post-Typhoon Dolphin conditions. After the storm drove an earlier heatwave that produced record readings above 36°C around August 9–10, the system’s departure allowed cooler maritime air and increased cloud cover to moderate temperatures back toward seasonal subtropical norms. Late-summer climatology, with typical daily maxima near 31–32°C when no strong high-pressure ridge or clear-sky amplification occurs, aligns with the observed outcome. The market’s 99.9% implied probability reflects this convergence of verified station measurements and the absence of any unusual synoptic forcing on the date. Only an unlikely post-publication revision in the absolute daily maximum or a redefinition of the reporting station could alter resolution.