There is a significant geographical definition risk. The resolution source 'Hong Kong Observatory' typically refers to the specific monitoring station at the HKO Headquarters in Tsim Sha Tsui, not the highest temperature recorded anywhere in the territory. In spring, the New Territories (e.g., Sheung Shui) are often 2-4°C hotter than the HQ. Users betting on the 'territory-wide max' instead of the specific HQ station data will likely lose. Additionally, reliance on the finalized 'Daily Extract' means initial real-time readings could be subject to minor quality control revisions.

March 22, 2026 - March 23, 2026: The price of the '26°C' option surged from 13.5c to 30c, while '28°C or higher' dropped from 33c to 22c. Reason: The market refined its positioning around HKO's updated '27°C' cap. Traders unwound over-optimistic bets on '28°C+' and hedged into '26°C' to protect against potential cloud cover capping the heat. March 21, 2026 (12:15-18:45): The price of the '23°C' option crashed from 29c to 3.5c, while '27°C' spiked from 20c to 32.5c. Reason: HKO updated its forecast in the afternoon, significantly raising the expected temperature to 27°C, directly contradicting earlier global models that predicted cooler, rainy conditions.

Significant divergence exists. Global weather models (e.g., Google/Weather.com) are still predicting temperatures around 23°C - 24°C for Hong Kong on March 24, which is far below the 27°C predicted by the local authority, the Hong Kong Observatory (HKO). The prediction market is correctly ignoring global models and tracking the HKO (the resolution source), causing a disconnect between market pricing (anchored at 27°C) and the data seen by the general public on standard weather apps (showing ~23°C).