Recent forecast model consensus from the Hong Kong Observatory points to an overnight low near the seasonal May average of 24–26 °C on May 19, with market-implied odds clustered around those values due to modest differences in projected cloud cover and low-level moisture. Subtropical humidity typically restricts nocturnal radiative cooling, while light winds and variable evening cloudiness can shift the minimum by 1–2 °C depending on exact timing of any frontal passage. Historical data show typical May minima between 23 °C and 25 °C, and the current outlook favors near-normal conditions without strong cold-air intrusions. Updated model runs and the next official briefing will clarify whether clearer skies or increased moisture push the reading toward the lower or higher end of the narrow range.