The closely matched probabilities for 31–33°C highs in Manila on August 21 reflect uncertainty in the southwest monsoon's (habagat) strength and timing, with PAGASA forecasting 32°C alongside a 40% rain chance amid ongoing moderate-to-heavy showers through the period. Persistent cloud cover and precipitation from the monsoon trough tend to limit daytime heating by reducing solar insolation and enhancing evaporative cooling, while clearer breaks could allow peaks near 33°C. Recent model runs and climatological baselines for August—when average highs hover around 30–31°C—support this narrow range, with trader sentiment incorporating potential shifts in monsoon intensity before the observation window closes.