Persistent cloud cover and widespread rain from a moist monsoon air mass are anchoring overnight lows in Shenzhen near 25–27°C for August 24, producing the market’s tight clustering around those outcomes. High dew points near 25–26°C limit evaporative cooling, while thick stratiform clouds suppress nocturnal radiative heat loss; southerly flow off the warm South China Sea further moderates temperatures. Multiple model runs show only modest variation in timing and intensity of showers, leaving little room for extremes below 23°C or above 29°C. Updated guidance from regional meteorological centers over the next 24–48 hours will clarify whether any clearing window develops before dawn on the 24th.