Recent Philippine Atmospheric, Geophysical and Astronomical Services Administration forecasts indicate partly cloudy skies over Metro Manila on May 18, with a chance of localized afternoon or evening thunderstorms as the southwest monsoon begins to influence the region. This pattern introduces key uncertainty in peak daytime heating, as variable cloud cover and convective activity can limit maximum temperatures to the 33–35°C range despite May’s typical high solar insolation and climatological averages near 34°C. Light winds and high humidity further modulate heat buildup, while the absence of strong high-pressure systems reduces the likelihood of extremes above 36°C. Traders’ closely matched probabilities around these mid-range outcomes reflect the sensitivity of the final reading—taken at the Ninoy Aquino International Airport station—to the exact timing and intensity of any showers in the coming days.