The closely balanced market odds between 30°C or higher and 20°C or below stem from short-term forecast uncertainty around the East Asian monsoon transition and variable cloud cover expected near May 20. Hong Kong Observatory seasonal guidance anticipates normal to above-normal temperatures overall, consistent with climatological May overnight lows averaging 24–25°C under southerly flow from the South China Sea. Recent model consensus points to persistent stratiform clouds and scattered showers that would suppress daytime heating while reducing nocturnal radiative cooling, keeping the minimum most likely in the 23–26°C range. Key differentiating factors include the strength of the subtropical ridge versus any transient trough that could enhance clear-sky cooling or briefly introduce drier continental air. Updated Observatory briefings and refined model runs through the weekend will provide the next clearest signals for resolution.