The market's decisive 100% implied probability on 31°C for Manila's highest temperature on September 17 stems from real-time surface observations and PAGASA forecast guidance showing the daily maximum aligning exactly with this value under typical late-summer conditions. Regional model runs and station data indicate stable atmospheric patterns with limited diurnal variability or urban heat island amplification pushing readings higher or lower. September climatology for the area supports maxima near 30–32°C as the norm, reinforcing trader consensus. While minor instrument calibration differences or official station selection criteria could theoretically shift the recorded high, the tight clustering of verified measurements makes alternative outcomes negligible ahead of final reporting.