**Forecast consensus points to a minimum temperature near 25–27°C on September 23, aligning with the tightly bunched market-implied odds.** Singapore’s equatorial location produces limited diurnal temperature swings, with overnight lows shaped primarily by cloud cover, thunderstorm timing, and radiative cooling under high humidity. Persistent southwesterly flow and expected late-morning to afternoon thundery showers—typical for the inter-monsoon period—will moderate daytime heating and influence how much the boundary layer cools after sunset. Official guidance from the Meteorological Service Singapore and global models currently clusters nighttime lows in the mid-20s Celsius range, though small shifts in shower timing or cloud persistence could alter the exact minimum by 1–2°C. Historical September minima average near 24–26°C, providing context for the narrow probability distribution traders have assigned across the 24–28°C band. Updated model runs and official briefings over the next 48 hours remain the key near-term catalysts.