Recent ensemble forecasts from the Hong Kong Observatory and regional models indicate the minimum temperature on May 20 will likely fall between 23–27 °C, driven by light southerly monsoon flow and partly cloudy skies that limit nocturnal radiative cooling. Typical mid-May climatology shows overnight lows near 24 °C under humid maritime air masses, with modest day-to-day scatter arising from variations in cloud thickness and weak trough passages over the Pearl River Delta. The close market spread reflects genuine forecast uncertainty in precise humidity and wind-speed thresholds that control the exact minimum, while seasonal outlooks continue to favor normal-to-above-normal temperatures overall. Updated numerical guidance expected within the next 48 hours will likely tighten the range ahead of the May 20 observation window.