**Persistent cloud cover, showers, and moderate northerly winds are the main factors keeping Hong Kong’s overnight minimum temperature on September 2, 2026, tightly clustered around 25–26 °C in forecasts.** Official guidance from the Hong Kong Observatory gives a daily range of 26–31 °C, while multiple numerical models and private forecasters project nighttime lows of 24–26 °C under mostly cloudy skies with a 35–60 % chance of rain or thunderstorms. High humidity (70–95 %) and light-to-moderate winds (north to northwest, 4–6 on the Beaufort scale) limit radiative cooling after sunset, preventing a sharper drop. Historical normals for early September place the mean minimum near 24.7 °C, but the current unsettled pattern—tied to a broad low-pressure trough and distant tropical cyclone influences—adds a slight warming bias at night. Model spread on exact cloud thickness and wind timing creates the close 36 % / 30 % market split between 26 °C and 25 °C, with lower outcomes requiring clearer skies or stronger northerly advection that current guidance does not support. Updated model runs and official briefings through the evening of September 1 will be the next key inputs for traders.