**Trader consensus on the lowest temperature in Taipei for September 18 centers on a narrow 23–25°C band because official forecasts and real-time observations show overnight radiative cooling under partly cloudy skies and light northeast monsoon flow yielding a minimum near 22–24°C.** Central Weather Administration data and station reports indicate a recorded low of approximately 21.6–22.9°C amid dew points around 21–23°C and humidity near 80–90%, which limited further cooling despite clear intervals. Model runs diverged slightly on cloud cover and boundary-layer wind, keeping implied probabilities for 24°C and 25°C tightly matched near 50% while lower outcomes like 20°C or below retained nearly equal weight. This reflects typical late-summer variability in the region, where urban heat retention and weak synoptic forcing produce small differences in the diurnal minimum. Updated observations through the night will refine the final resolution.