**Persistent southwest monsoon (habagat) activity across Luzon is the dominant factor shaping minimum temperatures in Manila for September 12.** Official PAGASA guidance and recent model runs indicate continued cloudy skies with scattered showers and thunderstorms, which sustain high humidity (often above 85–90%) and suppress radiative cooling overnight. This typical wet-season pattern points to lows in the 24–26°C range, consistent with September climatology near 25–26°C. Forecasts from sources including PAGASA, GFS, and ECMWF show limited day-to-day variability through the short term, with no active tropical cyclone expected to alter steering or intensity before resolution. The closely matched market odds across bins reflect genuine uncertainty in exact overnight minima due to localized rain timing and model spread in boundary-layer moisture, rather than any major shift in large-scale conditions. New PAGASA briefings and updated model runs over the next 48 hours will provide the key data points for traders.